Engine running rough.... Here we go again !

[bigdog]

Engine running rough.... Here we go again !

Had same issue last year, and think it may be related to ethanol gas.

Have a full tank of gas, leftover from last Fall and winterization. Treated gas will Stabill, back in late Fall as usual (the red stuff). Also fogged engine as usual.

Had boat out twice this season, only for short trips, and had no problems.
Actually, the engine was running 'great', full throttle wide-open !
I think I may have violated the 45MPH rule !

Yesterday, took boat out on water for about 30 min, stopped, anchored took a swim. Heading back to the dock, engine started running rough, and had to pull back on throttle to about 10MPH. Seemed to want to stall as I gave it more throttle. Got back to dock, w/o stalling or backfiring.

Last season had similiar issue, here's the steps I took:
- First thing added a can of 'Sea Foam'
- Checked pickup valve in tank
- Checked Anti-Syphon valve in tank
- Changed spark plugs
- Checked all spark-plug wires
(tested in the cover of darkness also for arcing)
- Changed Fuel filter (thought water in fuel?)
- Drained almost entire tank of gas (that was fun.. NOT ! )
then added fresh gas.

Problem seemed to come and go during operation of engine, but never really seem to totally go away?

Suggestions or thoughts on what the issue may be? Getting frustrated !

Thanks,
BD

[BroadHopper]

Is the big mistake. I read all over the INTERNET that 'Sea Foam' and ethanol do not mix. Other than that, it should be a go!

If you have a fibreglass gas tank, you should have it checked out. Ethanol and fibreglass do not mix.

There is an in-line fuel filter just before the carburetor. Unrelated to the fuel/water seperator. Check for debris in the filter.

[ishoot308]

"Treated gas will Stabill, back in late Fall as usual (the red stuff)."

Your problem is most likely fuel related.

The red stabil should never be used with ethanol gas in a boat. This type of stabil is alcohol based and is only sucking more water out of the air through you tank vents. Remember ethanol IS alcohol so by adding more alcohol you are making the situation worse. Seafoam is also an alcohol based product.

Dan

Edited to make the following correction: The newly formulated RED Stabil no longer contains alcohol and should be safe to use with ethanol fuel.

[robmac]

They continue to sell the red Sta-Bil and it is causing havoc with fuel syswtems everywhere. It sounds as if you've got some water in the tank which of course settles at the bottom. Before again trying to syphon it all out again I would dump a full 8 oz bottle of Startron into the tank and letting it run to try and clear it up. Not alot of options short of draining it all out,and then what to do with the tainted fuel. PM me BD if you need a hand.

[AC2717]

Sta-bil makes a product for ethanol gas now, i use it for my jetski, works great from what I can tell

[bigdog]

Thanks everyone for the info. greatly appreciated !

Before last season I was able to drain my entire fuel tank less 5 gal. I then burned the gas in my cars w/o ANY problems whatsoever.
But the draining process was painful, and took me forever, wasn't easy to do!

What are people's thoughts about adding a bottle of 'HEET' to the gas at this time ? This product is suppose to extract water from fuel. It's basically a 'Dry Gas', but suppose to be 5x more effective than reg. drygas.

Also, 'BroadHopper' recommneded, checking the 'in-line' filter before the Carb.
I checked the fuel line where it connects to the Carb, and there is 'no filter' in that connection. Fuel/Water separating filter is connected to my electric fuel pump, from there the line connects directly to the Carb. No other fillters in between ? Should there be one there ? Maybe last time Carb was serviced, they didn't replace at that location ? If there is suppose to be one there to begin with ? Unsure?

Engine is Mercruiser 4.3LX
Not the 190hp 3bbl Carb version
Mine has a 4bbl Carb, creating 220hp

Thoughts?

Thanks,
BD

[NoBozo]

Originally Posted by bigdog

Also, 'BroadHopper' recommneded, checking the 'in-line' filter before the Carb.
I checked the fuel line where it connects to the Carb, and there is 'no filter' in that connection. Engine is Mercruiser 4.3LX
Not the 190hp 3bbl Carb version
Mine has a 4bbl Carb, creating 220hpBD

The four barrel carb actually has a small "inline" filter AT the Junction between the carb and the steel fuel line. The BIG nut that attaches the fuel line to the carb has a Small filter hidden inside it. Carefully remove the nut and the filter should pop out. It has a spring behind it.

In the Clymer Mercruiser Manual it looks like a small "Cartridge" type filter. You can get a Clymer Manual at West Marine. (Recommended) NB

PS: Using HEET or DRYGAS at this time will NOT be of any benefit.

[jrc]

Are you so sure it's a fuel problem? It could be an ignition problem, have you checked the spark? People blame ethanol for everything these days. It's not always the problem.

You said the boat ran great on a few short trips but gave you problems when you stoped for a swim after a ride. It could be a heat issue, while you were swimming the engine was sitting there wrapped up tight. Could be the coil. What does you temperature look like when you're crusing, could you be overheating? When did you last check for a worn impeller?

[Belmont Resident]

I've not had a problem yet when following the directions on the bottle.
You also have a fuel filter/water seperator whichneeds to be replaced before you do anything.

[bigdog]

NoBozo,
I checked the fuel line at Card, where big nut attaches to the Carb. THere is a Spring in there but no filter ! Mmmmmmmmmmmm........
Question, if there was a filter in there to trap particles, wouldn't that clog up and stall and/or shut down the engine ? WIll get filter at marine supply store.

Jrc,
Impellor just changed, and engine temp running around 140 Deg. Actually low !
I have heard others say, a bad coil will cause this symptom, if it overheats...
Could be the problem? Although, the last two marine techs down here in Mass. said 'no way' it was the coil. Then again, there were wrong about some other issues..... Geniuses!

Then again, could be relatd to a dozen other things???

Installing missing fuel filter at Carb connection, and also checking fuel/water filter located before fuel pump. Could be water in there ?

Approaching simple things first, process of eliminatioon.....

Thanks,
BD

[NoBozo]

Originally Posted by bigdog

NoBozo,
I checked the fuel line at Card, where big nut attaches to the Carb. THere is a Spring in there but no filter ! Mmmmmmmmmmmm........
Question, if there was a filter in there to trap particles, wouldn't that clog up and stall and/or shut down the engine ? WIll get filter at marine supply store.

BD

Small filters will clog up very fast and shut down the engine. This little filter was intendd as a filter of last resort. The main fuel filter/water seperator was intended to do the major filtering. A missing filter indicates someone removed it to solve a problem tempoarily..and never replaced it. The dirt that the filter WOULD have stopped..is now in the carb.

BTW: An ignition coil that is old/faulty CAN overheat (and expand internally) and short itself out. When the coil is COLD on a cold engine, It MAY actually work...until it overheats and shorts itself out again. Everything else on the engine has been checked or replaced ...may as well replace the coil.

DOES the engine run fine when it is COLD..as in the morning when you first start it up..? ...ie, before the coil heats up. The coil is mounted/clamped to the engine, and engine heat will be conducted to the coil as the engine heats up....... NB

[Doyboy]

Here is what I add to the gas I put in everything other than my autos to battle the ethanol. I haven't had any problems coming out of the winter with any of my "toys" since I started using this stuff. I no longer use stabil.


http://mystarbrite.com/startron/cont...93/123/lang,en

[Irrigation Guy]

Originally Posted by AC2717

Sta-bil makes a product for ethanol gas now, i use it for my jetski, works great from what I can tell

This is true. The following is copied from their website.

Stabil Fuel Stabilizer(the red stuff)

STA-BIL Fuel Stabilizer is America’s top selling fuel stabilizer. Stored fuel can go bad in as little as 30-60 days causing gum, varnish and corrosion to build up in the fuel lines and engine. STA-BIL is recommended to be used AT EVERY FILL UP in all vehicles and equipment to protect against corrosion caused by today’s Ethanol-blended fuels.

Marine Formula STA-BIL Ethanol Treatment & Performance Improver (Blue stuff)

Marine Formula STA-BIL Ethanol Treatment & Performance Improver contains DOUBLE the corrosion preventers and more than FOUR TIMES the fuel system cleaner than in Regular STA-BIL to prevent against corrosion and deposit build up in Marine Engines. Use AT EVERY FILL UP to protect your boat or other marine equipment from the damaging effects of Ethanol in the marine environment.

Hope this helps about the misconceptions of the Red stuff.

[bigdog]

NoBozo,

Will install a new small inlet-filter at Carb connection, the one thats missing for some reason ? I suppose if junk gets past the fuel/water filter, it will definitely end up in the Carb. Then again, if that filter clogs up fast the engine will shut down starved for fuel !

Engine runs fine until it heats up to temp. about 140 Deg. and 30 min use, then the problem begins ! Could be the coil overheating and shorting out?
Think coils only run about $30 or so, so not a major investment, and would eliminate that issue, once an for all !

Thanks again for the info.
BD

[robmac]

BD,that is an easy cost effective fix. Coils don't last forever give it a shot and let us know.

[BroadHopper]

Factory coils have been a headache in the past. I switched to Jacobs coils and never had a problem. It is a much better coil and worth the money.

Jacobs was bought out by ACCEL and the line was incorporated into its line. ACCEL coils and MSD coils are an excellent substitute. It is very simple to replace and a good DIY project.

[bigdog]

Thanks for tip about coils and Mfg: Jacobs, MSD, ACCEL etc

What do you think about Mallaory, think they are one of the original mfg. of electrical coils, since coils were invented, they go WAY BACK !

Also, is Sierra a good alternative? These are used in a lot of applications where OEM parts are required. Think though they made be made in China ?

Can I buy a coil for my engine, besides a marine dealer or boat yard?
Thinking mabe NAPA? Suggestions appreciated about this!

BD

[NoBozo]

Originally Posted by bigdog

Thanks for tip about coils and Mfg: Jacobs, MSD, ACCEL etc

What do you think about Mallaory, think they are one of the original mfg. of electrical coils, since coils were invented, they go WAY BACK !

Also, is Sierra a good alternative? These are used in a lot of applications where OEM parts are required. Think though they made be made in China ?

Can I buy a coil for my engine, besides a marine dealer or boat yard?
Thinking mabe NAPA? Suggestions appreciated about this!

BD

Yes you can buy a coil from NAPA. BUT I suggest you buy a coil from a Mercruiser dealer to be sure the Match is correct."....and put it in yourself. No shortcuts. It's "Plug and Play".. NB

[NoBozo]

BD: Got your PM.

[MAXUM]

I had a very similar problem with my boat, same power plant. At first I was convinced due to the symptoms that the problem was fuel related, however it turned out to be an ignition problem. The coil could be the issue, however usually when those go, they just crap out and that's it. My problem was intermittent and ended up being the ignition pickup inside the distributor. It sits down inside the distributor housing. When I pulled it out I noticed that there was a fully exposed circuit board on the underside and the soldered connection points had this green and white corrosion on them. When I took it down to my local merc dealer and showed it to one of the mechanics there I questioned it's condition and sure enough he said that was a pretty common problem and that Merc had redesigned them. When I looked at the new one that board was fully sealed in resin and clearly done to prevent this from happening. Anyways I only mention this as something worth checking out. They take little time to remove. Not a super expensive part either, I recall it being about 50 bucks or so for one made by quicksilver.

[ApS]

Although I don't have specific experience with these engines, I like MAXUM's answer.

1) To paraphrase MAXUM's response: "coils generally work—or they don't".

2) When fuel is the problem...

A properly-running engine (using gas containing ethanol) has an exhaust odor that is "sickly-sweet".

The exhaust of "over-rich" engines (indicating fouled plugs, sticking float, bad wires) will smell strongly of raw gasoline.

One that is starved for fuel smells like nothing else I can describe. (Burnt fresh-cut grass clippings with a wet cigar thrown in? )

Also, fuel-starved engines will sputter, cough, and backfire.

[bigdog]

MAXUM,

Not sure about that 'Ignition Pickup' ? I do know I Marine Techs replaced:
Distributor Points/Rotor, Condensor...... Nothing mentioned by Techs, about 'Ignition Pickup' to me? Does not seem like a DIY project for backyard mechanic?

About the Coil, 'either working or not', the Forum comments have indicated that whne these things 'heat up' they can short and cause problems like what has been described.

Coil is original (1995), boat also was in and arround 'salt water' at different times.

Does the Forum still stand on their opinion about the coil issue ?
MAXUM makes a good argument about the coil and 'ignition pickup' issue!

Also, just more FYI about engine.
- Changed Plugs mid-last season. BTW old plugs looked pretty good !

Past symtoms of engine 'fuel starved' seems reasonable, as 'Acres Per Second' described: coughing, stalling backfiring. This was happening last season ! Replaced 'electric fuel pump' (wasn't cheap !), end engine ran much better. I was told by marine Techs, that the Pump contains a 'sliding ball' which can stick or totally locks up (thanks Mercruiser ! ) causing fuel starvation to Carb !

More thoughts anyone about the Coil replacement and cause?

Thanks,
BD

[bigdog]

MAXUM,
Do you think the soldered connection points on Ignition pickup. can be cleaned and reinstalled ? Or is complete replacement of this part required?
Your thoughts ?

FYI, getting to my Distributor in engine compartment, is like having to balance on my head upside down.

Damm those boat design engineers ! They don't think of accessibility by the boat owner to perform maintenance ! No thiought put-in when designing boat/engine layout.

Thanks again.
Bigdog

[MAXUM]

Honesty I don't know and my way of thinking is if the part, especially electronic is in any way faulty why not just replace it. What I didn't tell you was that it took me several trips out on the lake to figure out what the problem was and twice had to be towed in, thankfully I did not go out alone so the towing was somewhat expected. By that time whatever I found to be wrong was definitely going to be replaced.

I'd at least pull it out and look at it although some may not have outward signs of being bad, mine it was plain as day. The service manual I have does not give any kind of diagnostic tests that can be done. Granted I have a cheapo Clymer manual, if I had a mercruiser manual I'm sure it would have a test that could be performed with a multimeter to ensure it's within spec. Also what makes me think this may be an issue is that 99% of the problems I've dealt with in regards to ignition module failures (oh I'm an ex Toyota technician) has been heat. Things are fine till you hit operating temperature then the sporadic run time problems rear their ugly heads.

OK far as coils go. Again usually when they go they just plain go. Be aware that there are various makers of coils out there, some good, some not so good. There was mention of Mallory in an earlier posting. Don't know about them but I'd stick with a Delco or Denso. If you are going to put a new one in, before going through all that work to install it, shake the coil and be sure it's got oil in it. Matter of fact I do that at the parts store!

The ignition pickup is inside the distributor housing. At least that's what I've always called it, looking in my service manual they call it the ignition sensor, the box it came in something like ignition module assembly. Call it what you want I guess. If you pull the cap off and pull the rotor off you'll see it, there are a couple of small screws that hold it in place and there is a notch in it where the rotor blade rotates through. Yes these are not exactly easy to get to depending on the way your boat is made. I'm fortunate in that I can pull the engine box off and get it out of the way and lift the rear sun pad out of the way. For those that have the bench seating, yeah it's a chore. Replacing the part is not hard and takes little mechanical know how, just need to get in there which is half the battle. For reference I have a 2003 4.3 with the thunderbolt solid state ignition and no EFI. If it weren't such a pain to get at it I'd pull my distributor cap and take a pic for ya. I was just out in the garage looking for the original box it came in so I could give you a part number, but it looks like I may have pitched it.

BTW if you're going to go that far might as well replace the rotor and cap too. I did just because I was already in there.

Good luck!!

[bigdog]

Thanks again MAXUM. WOW a Toyota Tech Rep. impressed !

What you've desribed about 'ignition module assbly' makes sense to me.
I've heard repeated stories about this problem from many sources, both here on Forum and other boat owners..

Will inspect that ingnition module for corrosion, and also check online for replacement part and cost. Will probably buy at local marina !

Honestly, I havd never known anyone who had to replace their coil.. Not saying it doesn't fail, but seesm like an unlikely cause, compared to 'Ignition Module'.

Thanks,
Bigdog

[trfour]

[QUOTE=bigdog;131248

"Coil is original (1995), boat also was in and around 'salt water' at different times."

Thank you... Very important to give us an idea when asking for help to give the year that the boat was manufactured...

Worn distributor shaft bushings can cause a multitude of problems and can cause the rotor to strike the distributor cap contacts, usually dislodging the rotor contact plate and causing erratic ignition timing problems... [ Kind of like inhaling cheerios for us humans ]!

Now,... I know that nobody wants to listen, however, the time to do basic maintenance and check your anti tow vehicles life line, is during off season. Shrinkwrap ain't going to get her done!
However, should you like paying a higher premium, and enjoy Company, tow US is not far behind.

Auto, boat, car, heilicopter, plane or truck, got my fix in and on route 66.
Last, but NOT least, just wanted to say a Big HI, to the Noonan's!!!!
tenfour?

____________________________________

T

[MAXUM]

Originally Posted by bigdog

Thanks again MAXUM. WOW a Toyota Tech Rep. impressed !

What you've desribed about 'ignition module assbly' makes sense to me.
I've heard repeated stories about this problem from many sources, both here on Forum and other boat owners..

Will inspect that ingnition module for corrosion, and also check online for replacement part and cost. Will probably buy at local marina !

Honestly, I havd never known anyone who had to replace their coil.. Not saying it doesn't fail, but seesm like an unlikely cause, compared to 'Ignition Module'.

Thanks,
Bigdog

No problem. Hopefully that cures your ailing boat! Used to be a Toyota tech, wrenched for a few years, got bored with it and did a career change. Still do it though, just not for a living.

Good luck with your repair. Let us know how things turn out.

[XCR-700]

Originally Posted by MAXUM

Honesty I don't know and my way of thinking is if the part, especially electronic is in any way faulty why not just replace it. What I didn't tell you was that it took me several trips out on the lake to figure out what the problem was and twice had to be towed in, thankfully I did not go out alone so the towing was somewhat expected. By that time whatever I found to be wrong was definitely going to be replaced.

I'd at least pull it out and look at it although some may not have outward signs of being bad, mine it was plain as day. The service manual I have does not give any kind of diagnostic tests that can be done. Granted I have a cheapo Clymer manual, if I had a mercruiser manual I'm sure it would have a test that could be performed with a multimeter to ensure it's within spec. Also what makes me think this may be an issue is that 99% of the problems I've dealt with in regards to ignition module failures (oh I'm an ex Toyota technician) has been heat. Things are fine till you hit operating temperature then the sporadic run time problems rear their ugly heads.

OK far as coils go. Again usually when they go they just plain go. Be aware that there are various makers of coils out there, some good, some not so good. There was mention of Mallory in an earlier posting. Don't know about them but I'd stick with a Delco or Denso. If you are going to put a new one in, before going through all that work to install it, shake the coil and be sure it's got oil in it. Matter of fact I do that at the parts store!

The ignition pickup is inside the distributor housing. At least that's what I've always called it, looking in my service manual they call it the ignition sensor, the box it came in something like ignition module assembly. Call it what you want I guess. If you pull the cap off and pull the rotor off you'll see it, there are a couple of small screws that hold it in place and there is a notch in it where the rotor blade rotates through. Yes these are not exactly easy to get to depending on the way your boat is made. I'm fortunate in that I can pull the engine box off and get it out of the way and lift the rear sun pad out of the way. For those that have the bench seating, yeah it's a chore. Replacing the part is not hard and takes little mechanical know how, just need to get in there which is half the battle. For reference I have a 2003 4.3 with the thunderbolt solid state ignition and no EFI. If it weren't such a pain to get at it I'd pull my distributor cap and take a pic for ya. I was just out in the garage looking for the original box it came in so I could give you a part number, but it looks like I may have pitched it.

BTW if you're going to go that far might as well replace the rotor and cap too. I did just because I was already in there.

Good luck!!

I too have had problems several times with the ignition module inside the dist on my 23' Carlson 5.7 Mercury I/O with thunderbolt ignition.

Its a piece of JUNK as far as I am concerned and part of the reason that boat is down with a bad motor.

The module died while I was prepping it for winter and I thought well its good enough and I'll fix replace the module again (3rd time for me) in the spring. Well I guess I didnt get enough coolent run through it and the motor got a freeze crack,,,

What really got me was that the motor had very low hours and ran GREAT otherwise. Errrr

[Baja Guy]

Here is a link to free downloads of the Mercruiser factory manuals. Find your year and engine and it will show you what the part Maxum refers to looks like and how to change it. http://forums.iboats.com/showthread.php?t=342393
To do that service be prepared to use a pair of screwdrivers to 'leverage" the rotor off the distributor shaft. Mercruiser says that's how you take it off. It's done that way because the rotor is stuck to the distributor shaft with Locktite.
You can inspect the ignition module without removing any parts though, I'd say do that first. All you do is lift the distributor cap far enough to see inside the distributor. You can do that with the plug wires still attached if my 5.7 with Thunderbolt ignition is any guide.
I believe Mercruiser says to check for a good solid connection from the sensor to the board. The connection can fail and split, in which case you can get intermittent problems like Max had.

I found corrosion on the underside contacts of my distributor cap this spring. Check that too. I agree with doing the cap & rotor as a preventive step. They cost about $40 for the set.
I'm with Maxum, fix it as soon as you even think it's a problem, that way you don't need a tow home or worse.

Pete

[chunt]

I had the same problem, the boat will not rev up after warm. Found the thunder bolt ignition module was the problem. It is bolted onto one the heatexchanger manifolds. The trigger from the pickup, inside the distributor, goes to this module. It contains the advance curve and triggers the coil to fire. I found the problem by putting ice on the module when it was hot, this allowed th motor to rev up again until it overheated again.

[Baja Guy]

"Cool" diagnostic technique, I couldn't resist...where did you get that idea?

[bigdog]

Regarding the gnition Module Assembly...

Wow, never knew this little part (Ignition Module), have caused so many issues, for so many people ! Some of your stories must have been frustrating, especially if you got stuck and had to be towed !

FYI, Distributor Cap & Rotor changed last Fall.

Well, I was able to get to my Distributor. Had to dismantle several pieces of couling/covers around the engine. Like I said, my engine compartment is extrmely difficult to work around. Even with these pieces removed, I don't have a easy access to the Distributor.

Distributor had three screw type bolts which holds it in place. And one phillips type screw, also on the cover which didn't look like the others ? Not sure what that screw is for?

Pulled Dist. cap off with plug wires intact. I can see inside the Dist., and see Rotor on top. I cannot see anything else ? I tried to pull off the Rotor, but it didn't budge. I think I remember that someone said that it may be held in place with 'Locktite' ? Anyway this is as far as I got, and had to stop cause of darkness.

Afraid to pry-off Rotor with 2 screwdrivers as somene indicated. for fear of breakage ! That wouldn't make my week !

At this point I may haul boat to marina in Gilford area, to have them complete the job. Everything is basically dismantled at this point, and think marina should be able to install the Ignition Module in less than an hour ?
Ya Think?

The only problem now, is finding a marina that will do this now, just before the 4th of July holiday w/e ?

Going to make some quick calls in the morning to see which marina can accomodate.

Oh, A BIG THANKS 'Baja Guy' for sharing that Mercruiser shop manuals with the Forum ! http://forums.iboats.com/showthread.php?t=342393

BD

[bigdog]

News Update !

Got new 'Ignition Module' installed !!!! Yippee!

Inspected old Module, and appeared to be rusted, pitted, with white-greenish corrosion on contacts. What a piece of JUNK Merc made for this part !
Basically, and open circuit board, with wires. Apply moisture, and you've got some real problems. New Module encased in Resin, so Merc must have know they had a problem with the original design.

Hoping this was the problem, and the fix, and can put this issue to sleep, once and for all ! Crossing my fingers, and saying a prayer.

Will test boat on water probably Thur.

BD

[NoBozo]

Originally Posted by bigdog

News Update !

Got new 'Ignition Module' installed !!!! Yippee!

Inspected old Module, and appeared to be rusted, pitted, with white-greenish corrosion on contacts. What a piece of JUNK Merc made for this part !
Basically, and open circuit board, with wires. Apply moisture, and you've got some real problems. New Module encased in Resin, so Merc must have know they had a problem with the original design.

Hoping this was the problem, and the fix, and can put this issue to sleep, once and for all ! Crossing my fingers, and saying a prayer.

Will test boat on water probably Thur.

BD

Excellent news BD. Stay close to home until you are positive...Yeh Yeh..I know...maybe a better word is Comfortable...before you venture out beyond paddling distance....unless you are sure of a (FREE) tow. NB

[bigdog]

NoBozo, good advice ! Wil stay close to home port for a while.

Will have wife on next boat outing, so sure don't need to breakdown.
She's insisting on going on trial run ! I warned her the possible consequences.

I'll be bringing my 1/2" wrench just in case..... If engine produces same symptoms, the brass plug will be pulled in the middle of the Broads !


Wife and I are just about ready to switch to 'Sail' after this !

BD

[MAXUM]

Bigdog-

Based on your description of the old module I'd say you found your problem. Awesome, glad you got it fixed in time to get out there and enjoy the lake!

No question that old module was a bad design, not sure if it's something that is unique to just Merc or if Volvo suffers from the same flaw. They do after all use the same 4.3L Chevy engine. How much similarity there is between the two would be interesting to know. I can't imagine the ignition systems are all that different between the two. What ever the case the new design is far and away superior to it's predecessor.

[NoBozo]

Here's a GOOD site to find Mercruiser Parts with Prices. This is not a discount place but offers what I believe are Retail Prices so you can have a starting point when shopping for parts. NB

http://www.mercruiserparts.com/mercruiser_parts.asp

[MAXUM]

Originally Posted by XCR-700

I too have had problems several times with the ignition module inside the dist on my 23' Carlson 5.7 Mercury I/O with thunderbolt ignition.

Its a piece of JUNK as far as I am concerned and part of the reason that boat is down with a bad motor.

The module died while I was prepping it for winter and I thought well its good enough and I'll fix replace the module again (3rd time for me) in the spring. Well I guess I didnt get enough coolent run through it and the motor got a freeze crack,,,

What really got me was that the motor had very low hours and ran GREAT otherwise. Errrr

XCR-

Food for thought. When I winterize my boat I completely drain the block and manifolds of as much water as I possibly can, then backfill with antifreeze, the RV/Marine stuff since it's non-toxic. Now I'm not sure where the drains are on the 5.7, but the 4.3 I have has a total of 5 drain plugs. One on either side of the engine block, one on the bottom of each manifold and one just below the water pump next to the fuel/water separator.

Once I have all the raw water drained out I put the plugs back in then remove the top side of the coolant hoses on the front of the engine. They all come together onto what looks like a distribution point, I think (going off memory here) there are 4 total, two that are small and two that are large. Anyways I backfill the engine block by pouring the antifreeze into those hoses till they are full. One of the smaller hoses goes directly to the stern drive so after pouring antifreeze into that hose for a bit you can hear it dripping coming out the raw water intake. When I do this I already have the boat and trailer in the garage and up on jack stands with the stern drive as far down as it'll go without hitting the floor. I store it all winter like that. Never had any freeze up problems and I can tell how much antifreeze is in the engine block and manifolds based on how much I put in which is usually at least 2-3 gallons. Now some say you can just drain the engine, manifolds and that's good enough, maybe but any untreated water left over will freeze and depending on where it is could cause problems so I figure it better to be safe than sorry. Antifreeze is cheap, engine blocks or stern drives not so much!

Oh I forgot the most important part!! All that water and what little antifreeze may spill into the bilge should be cleaned up - then optionally wax the bilge so it's nice an pretty to look at

[robmac]

I agree,when I winterize I go and get 6 gallons of RV antifreeze. I run 3 through the engine pull the drain plugs let her drain completely then pull a top hose and run 2-3 gallons back ib. Been doing that for 20 plus years and never an issue in the spring. Depending on where and how bad she's cracked you can have it welded. Did it a couple of times with race engines,it's a pain but not as bad as paying to replace.

[bigdog]

Reporting back to the Forum on test run....

Replaced 'Ignition Module Assembly' at the suggestion of a few on this forum.
Again, when I removed the original part, I was shocked to see this part
'basicall an exposed printed circuit board'. are you kidding me !
At least the new design of this part is encased in resin, totally protected from the environment or heat.

The maine engineer geniuses really blew this original design ! All those years studying at an engineering college and all that money for tuition.....
and that was the best design they could come up with..... Amazing !

I digress...... Back to the results......
Have taken boat on trilal runs now 3x, for more than 4hrs. Various levels
of speed/RPM's. NO ISSUES ! PTL !!!

Previous boat outings have produced engine caughing, backfiring, and stalling after only 20-30 min of use. Almost needed a tow a couple time, but was able to limp back to port.

Hopefully, this issue is finally resolved !
Guess I can put away my 1/2" wrentch, and thoughts about pulling the plug ! At least for the time being..... TBD..........

Oh, one last mention about Winterizing engin I'd like to get folks thoughts.

My guy who winterizes my boat, also runs a car dealership.
He just drains all headers, hoses, and any other orifices of water. He does not add anti-freeze, never has. His thoughts are, if there is no water in the engine, there is nothing to freeze ! Says he' never lost or had an engine crack as a result of this process yet ! Thoughts ?

Thanks everyone for all the advice, especially to MAXUM, who I believe
came up with the original diagnose, only through a similiar situation.

BD

[BroadHopper]

I usually run 4 gallons of antifreeze and forget the draining. Never had a problem. Advantge of keeping the antifreeze in the motor is a rust preventative. There is no air in the block to form rust.

[NoBozo]

Originally Posted by bigdog

The maine engineer geniuses really blew this original design ! All those years studying at an engineering college and all that money for tuition.....
and that was the best design they could come up with..... Amazing !

IBD

When we designed that module, the "Bean Counters" wouldn't let us encapsulate the circuit board because:

1. It would be Too Expensive.

2. Encapsulating the module would violate the Laws of Planned Obsolescence and the module would last longer, thereby slowing down future sales NB

[bigdog]

NoBozo....

No dig inteneded toward you.. Didn't knoe you were in Enigineering ?

I work in a major Fortune 50 Corp.(not 500). I totally undersatnd the mentally and decisions of Senior management when making any cost effective decisions. It's not about quality, it's about the bottom line, and future sales.

You're also correct in your statement about 'Planned Obsolescence’!
What was I thinking, I should know better !

BD

[RI Swamp Yankee]

Originally Posted by bigdog

.... when I removed the original part, I was shocked to see this part 'basicall an exposed printed circuit board'. are you kidding me !
At least the new design of this part is encased in resin, totally protected from the environment or heat.....

Sorry if this is a bit off topic but several years ago I had alternator problems with a Dodge Caravan. It would fail to charge ONLY when the weather was wet!!! ... long story short ... I found part of the engine control circuit board that controlled the charging was not encapsulated, the rest of the board was ok. Dried the PC board, encapsulated it and end of problem.

[bigdog]

Reaching for that 1/2"wrench of mine ! Ready to switch to 'Sail' !

My problem with boat has reared it's ugly head again....
After 3 successful outings on boat w/o any problems (more than an hour each outing), my engine started to display signs of coughing, backfiring, and stalling.

The three ladies onboard did not appreciate the ride, but I was able to limp back to the dock w/o being towed. I did manage to get in a swim first!

Was only on the water for about 45 min. Had engine at 3/4 throttle to half speed for half the time, then down to wake speed going through Governor Island bridge and back. Soon as I passed NWZ on Varney Point side of GI bridge I opened her up, that's when the trouble started !

Now, I just replaced the Ignition Module in Distributor. Since that time all has been well, up until now. That part/circuit board, was definitely bad, corroded, rusted, etc.

I think I have indicated all the parts replaced, and things checked.

FYI, I am still running on some of last Fall's gas (40 gal tank). My suspicion is that some slug at bottom of gas tank is getting sucked into Fuel pump, filter, or Carb. causing the symptoms mentioned at beginning of this email.
BTW, I changed the fuel filter beginning of season.

Some Forum members suggested that they thought this issue was related to a bad Coil, and when running for a while and heated up causing the problem. But others had stated that when a Coil goes, 'it just goes', and dies!

So what is everyone's thoughts at this point. Need some good suggestions.

BD

[robmac]

I would strongly recommend a coil replacement. When ignition parts begin to fail they wear on the others. For about 20 dollars it would be my way to go. You could also put an inline spark tester an an easy to see plug when the problem rear its ugly head and look at the strength of the light or if it's cutting out completely.

[Resident 2B]

Since you still have some of last years gas in the tank, I would look at the water in the water/fuel seperator if it is the visible type or I would change the cartridge if it was the cartridge type. If you have a lot of water there, you need to address that.

Old fuel can be a killer this time of year, especially old fuel in a tank below half full.

Good luck!

R2B

[MAXUM]

The symptoms you describe just do not lead me to think it's a bad coil. All things being equal it's possible but unlikely.

Knowing that you're on last years gas would be suspect. I'd consider replacing the fuel/water separator because this ethanol laced gasoline is prone to attracting water/moisture especially with temperature change. If you did treat the gas when you winterized it's less likely this would be a problem. Really at this point it's almost like the best thing to do is to get the boat into a state where it's running like crap and start troubleshooting whether it's a gas or spark related problem.

Some other things that come to mind

Bad ignition wires, especially the one that you have coming from the coil to the distributor. Even if the wires look good you may have a situation where the insulation has begun to break down and is partially grounding out.

Moisture is getting into the distributor. This condition usually makes the engine run rough all the time though.

If you're carbed you may have a situation where you've got a float that's getting stuck.

Vacuum leak somewhere?

[bigdog]

MAXUM,

Just to answer a few of your concerns and suggestions:

-Gas treated before winter storage
-Carb rebuild a year ago, all new parts including 'float'
-Replaced Ignition Module in Distributor (ran fine after replacement for 3 outings-1 hr each time)
-Ignition wires look good, insulation looks almost new (checked ignit wires at night with engine running, looking for arcing, NADA !)
- Not sure about Coil wire from Coil to Distributor. Never replaced.
-Vacume leak? No idea, and no idea how to test

Hopefully, going to check engine spark this w/e with in-line plug tester. Will test at spark plug first, then move back to Coil.

Interestingly, I called one of the biggest marinas on gthe Lake, and they said they've had a recent request for Coils, and can't keep them in stock fast enough.

Will report back to Forum test results.

Thanks,
Bigdog

[MAXUM]

With the plug wires, if you can see an external arch that means they are really in bad shape, however you may not see a bad on bleeding off partial current with the naked eye. If however this was a problem I would have expected that even with the replacement of the module this behavior would have continued to some degree.

Bottom line, hard to give you advice on what to look at next without some additional information.

[Irrigation Guy]

I'd put a set of ignition wires to it, especially since it sounds like you never have. They are not huge $$, and will eliminate a possible cause. Also, other tune-up parts if not previously replaced(cap, rotor, and plugs). I'd also change the water seperator(empty into clear container to check for water sinking to bottom), and fill with fresh gas(hopefully you'll then have a good percentage of new gas).

Please let us know how you make out.

[bigdog]

To Local Realtor

Have never changed ignition wires since I owned boat. Boat is 15 yrs old, I have owned for 4 yrs. not sure of what was done by previous owner(s) ?

Boat actually has low hrs. Only 200 +/- on meter.

Did perform the gas check for water in gas, but couold not see any visible signs being present.

Got an estimate for new Ignition wire set from marina, OEM for $65.

Can I use a standard automotive set of ignition wires from NAPA or similiar
to fit my Merc 4.3LX. It's basically a Chevy 220HP ?
Think wires are either 7 or 8MM Dia. ?

Just thinking it would probably be a lot cheaper buying from automotive parts store than marina.

Thoughts anyone?

Thanks,
BD

[robmac]

yes you can get them from NAPA, alot more cost effective.

[Irrigation Guy]

Yes you can use ones from NAPA, but beware of ones you must assemble yourself or other cheap one. If you are buying quality ones, which I hope you would, you will not save a ton of money on them vs marine quality ones.

IMHO, I would spend a little more for quality you will not be buying them again for a while.

[robmac]

I have a question, what ignition coil do you assemble? Having been in the business for over 35 yrs never bought or installed a coil kit so just wondering.

[Irrigation Guy]

Originally Posted by robmac

I have a question,what ignition coil do you assemble? Having been in the business for over 35 yrs never bought or installed a coil kit so just wondering.

LOL....I think he asked about buying ignition wires at napa, so I replied about ignition wires.

Maybe go back and re-read his post directed to me?

Sorry for the confusion.

[Charlie T]

Got an estimate for new Ignition wire set from marina, OEM for $65.

Can I use a standard automotive set of ignition wires from NAPA or similiar
to fit my Merc 4.3LX. It's basically a Chevy 220HP ?
Think wires are either 7 or 8MM Dia. ?

Just thinking it would probably be a lot cheaper buying from automotive parts store than marina.

Thoughts anyone?

Thanks,
BD

I'd go with the Marina's OEM wire set. Automotive sets are going to be custom length for a Automotive application. The Marine sets are custom length for the Marine application. With Auto wires you will be either too long or too short to properly "dress" the wires in the Marine looms.

On another note and with all due respect, you've been chasing this problem for a year now. I fully understand the "do it yourself" method but if you don't have the real life experience and knowledge to properly diagnose and repair this problem wouldn't it make sense to find a very good marine mechanic that has factory training from your engines manufacturer and have it repaired correctly once and for all? A factory trained guy that does it for a living will probably have an inventory of the proper parts and the proper test equipment and be able get you on the water without further problems. He will (should) also guarantee his work!

The boating season is too short to waste it asking questions on the internet. People here are trying to be helpful but sometimes you need to hear the problem, see the problem or feel the problem in person to know what it really is, suggestions that amount to throwing parts at a problem until something sticks aren't doing you any good. You have a problem that has been difficult to properly diagnose and fix. Internal combustion engines rely on "Fuel, Compression and Ignition" you can change, change,change until you stumble on the problem by accident or you can pay the man once and be back boating and enjoying the lake.

Just my $.02 Good luck with fixing your problems.

Charlie

[bigdog]

Charlie,

I hear ya' loud and clear about chasing the problem, and that's what I seemed to have been doing..... Been frustrating to say the least !
I apprecaite your commnents, TY !

I have sought professional marine help in two instances, In both cases,
the so called 'marine tech professionals' basically just tried to approach by process of elimination, by replacing parts one at a time, taking the
"Let's try this and see what happens" apporach, rather than diagnose the problem from the ground up. The prior appraoch seems to be common across the marine repair business, am I wrong?

That being said, I cannot called these particular marine techs 'Professionals'. I have spent countless $$$, with the 'so called' porfessionals, w/o haiving the issue resolved. I have to take some blame,
I guess for maikng the wrong choices for marine service repairs. 'My Bad' !

Not pessimistic by nature, but who can you trust these days, to stand behind their service to 'do the job right' ? I would place more trust and recommendations, in this Forum from boaters, who may have experienced similiar situations.

I would love to put these engine problems behind me and enjoy the rest of boating season. Continuing to diagnose, will keep Forum informed of progress.

Just my $.02

BD

[Irrigation Guy]

BD...certain ignition only have a certain life span and if you have not changed them I would do so. Even if you consult a professional again, they will likely want to eleminate these parts as a cause and suggest you change them. Why pay a professional to change what you can change yourself?

Cap, Rotor, plugs and wires all fall into this catagory as far as I am concerned. Some of these have a different life span too.

I agree some work is best left for professionals but I try and eliminate some of the easy stuff first.

[bigdog]

OK Forum members, I believe I have identified and fixed my problem.

DRUM ROLL PLEASE !!!! Coil ! No @*^$(*@#$(#&%# Coil !

Yup, I believe this was the underlying issue. Knock on wood !
Many thanks to the following who indicated that this could be the problem:
JRC
NOBOZO
robmac
BroadHopper
Maxum

Although, I believe the 'Ignition Module' I suspect was a contributing factor, being the open circuit board was corroded and rusted electrical wires like threads!

Replaced the Coil shortly after my last thread reply, last week in July.
Have made about 6 boat outings with the family without any engine issues as previously described: coughing, backfiring, stalling

Each outing lasting 1-2 hours of actual engine running time. Engine running at different speeds from wake-speed to full throttle.

Several folks indicated that when the coil is COLD it works fine, but when it heats up,it may be shorting itself out. When engine cooled down it would run fine again. I believe this is exactly what was happening, because this was the exact circumstances.

Also been adding fresh 89 Octane after each boating trip, keeping the tank full. Added Startron to tank, following product mfg. instructions.

So far so good. Hopefully, the problem appears to be now a mute issue.
I will take a picture of Coil to upload and Post. Rusted on outside of body, and inside of terminal tower looked corroded !

Thanks again for everyone input, greatly appreciated !

Bigdog

[robmac]

Glad to hear the issue is finally gone BD now just enjoy the remaining days of the season.

[VitaBene]

Glad you got it- the worst problem was likely doubting your boats reliability.