Gas-Mechanical problem with boat engine

[bigdog]

Hi folks.....

Hope someone can give me some suggestions about a recent problem I had this weekend, when launching the boat for the first time this season.
Prerequisite:
Engine: Mercruiser 4.3L, AlphaOne O/D

After launching the boat we cruised around for only about 30 min, anchored, had lunch, even a swim Brrrrrrrrr.

When we started back after several hours, we started back to shore. Got the boat up on plane, and after a few minutes started to cough, sputter, then finally stalled. I was able to restart the engine, but only move at wake speed. Stalled another dozen times before arriving at dock ! engine was definitely was gas deprived ! Whew ! MADE IT ! Anyway, got the boat on trailer and home.

At the end of last season, I made sure gas tank was full. Had boat winterized, including fogging engine, Startron and StaBil additives.
Also, changed gas filter (large water separator type).

Going to remove that filter and dump into gals jar, to check for water/gas separation. Also going to check and change out 'inline filter' to carburetor.
Checked gas cap also.

Can the car. get vapor lock ? Also, any other suggestions would be greatly appreciated ! My marine mechanic told me to bring to him to check, but want to do everything I can before making that move $$$$$.

Thanks,
Bigdog

[nightrider]

you will most likely find the fuel/water seperator 99% water. Empty it and start the process all over again. Run it for a while then empty into a glass container again and check for water. Don't throw the effluent overboard. Put it into a metal pail and burn the fuel off the water....on land, not on the boat.

[Chris Craft]

Another thing that I have seen happen is the fuel lines deteriorate with the new fuel and break apart. This can clog up the fuel filters, and or the hose can collaps inside making the motor fuel starved. Look for pieces of rubber in with your filters. Thank you Ethenol!!!!

[chipj29]

Have you changed your spark plugs? That stabilizer and fogging oil will do a number on them.
Also, how old is the gas? If it is still last seasons gas, you might want to drain it out and put in nice fresh gas.

[PC31]

The boat doctor from Boating magazine always suggests hooking up a 6 gallon tank of fresh gas. If the problem goes away the culprit is in the tank. Drain it and start again.

[SIKSUKR]

If you put fuel stabilizer in the fuel last fall,I would doubt very much that the fuel itself is a problem.Water in it however,could be another story.

[bigdog]

Thanks everyone, learned a few new things here I wasn't aware of.....

Didn't know that the fuel lines were rubber coated on the inside, thought these were strickley metal line feeds ? I can definitely see a problem
with any rubber lining breaking down with ethanol base gas.
Will look for pieces of rubber in with your filters as suggested.
.
Also, plugs were not changed last year, on the radar for this season.
I don't change out every year, because really don't see the need, as I probably only put 50+ hrs on engine in any given season. Plugs should last
double that age. With the gas additives and stabilizers, used for winterization
I can see a potential problem with plugs building up with gunk !
Plan to change out plugs this week.

Also going to replace ignition wires and distributor cap. Does 'rotor', usually need to be replaced ? And is this difficult to remove this off the top of distributor ? On rotors at least on cars, you just pulled up and off.
My understanding is that on Mercruisers (at least mine), you must position two screwdrivers on either underside of rotor/sensor wheel and pop-up as one unit ? Also, I guess you must adjust the carbon tang on rotor, between rotor and tang ?

Last, I know in Mass. you cannot purchase gasoline, whether on land or at a marina, without the ethanol additive, it's the law. Is this true in N.H. ?

Comments and suggestions are always appreciated !
Thanks everyone !

[chunt]

Another possibibility is the ignition module. You notice this more when the motor is hot, than when cold. Boat will run smoothly then die. After letting the module cool for only a couple of minutes, the whole cycle will begin again. When winterizing the boat, some people remove the ignition HV wire and allow It to arc to the coil negative terminal. This is how the module gets zapped.

[gtxrider]

The rotor should be easy to replace. It is either a slip on or held on by two screws. (don't drop the srews!) I am assuming the engine is fuel injected. Suspect bad fuel either old, water or blocked filter/lines but I had misfires due to a bad distributor cap. GOOD LUCK!

[Kamper]

Before you buy all that stuff, start with the easiest and cheapest of the suspect areas unless something turns up to point you along. The plugs you can probably get by with cleaning them but they're fairly cheap and easy to do anyway.

Good luck!

[Wolfeboro_Baja]

Originally Posted by bigdog

Also going to replace ignition wires and distributor cap. Does 'rotor', usually need to be replaced? And is this difficult to remove this off the top of distributor? On rotors at least on cars, you just pulled up and off.
My understanding is that on Mercruisers (at least mine), you must position two screwdrivers on either underside of rotor/sensor wheel and pop-up as one unit? Also, I guess you must adjust the carbon tang on rotor, between rotor and tang?

It's always been my experience (when working on my cars) that if you replace the distributor cap, replace the rotor as well. I can't imagine the rotor would be that difficult to remove. Like gtxrider said, the rotor either slips on/off or is held by 2 screws and they'll usually be on top of the rotor, not underneath.

Just my 2 cents..................

[bigdog]

Well.... Just made my first inspection of things....
Only had enough time during lunch to take a quick look !

I tried to remove the water/filter, but it wouldn't budge ! Tried to put a oil filter wrenth around filter but couldn't get a good grip. Going to buy a 'cap type' wrentch and give it a try.

I checked the 'inline' gas line to the carb. GUess what "NO FILTER' in the line.
What moron worked on this part of the engine last, wasn't me !
Anyway, I have a new in-line filter I bought last year and never installed. Problem now is I don't have the other parts: Spring, rubber gaskets.
Back to the dealer I guess?

Checked around the battery/coil are and notices some green corrosion building on coild connection. Going to clean this up, when I tackle the other stuff !

I have been told to use a product I think is called 'Sieze Free' ?, to coat spark plugs threads before installing, to prevent locking up in cylinder head.
Does this stuff really work ?

Thanks again for everyone's help. LOVE THIS FORUM !
Invaluable information!

Bigdog

[Chris Craft]

I am sure you wires are fine. Wires last for ever in boats because they do not have to deal with the heat of a car. Cap and rotor are probably ok but take a look inside for moisture and cabon build up on the inside. If you see moisture whipe it out and spray it with brake clean.

Some one mentioned hooking up the 6 gallon bounce around tank. This is a great idea.

If your filter wrench fit but would not grab put electric tape on the inside of the wrench and try again. It will help grab the filter better. Make sure you put a bucket or large rag under the filter so that you do not drop lots of gas down into the bilge (KABOOM!!).

[TomC]

Originally Posted by Wolfeboro_Baja

It's always been my experience (when working on my cars) that if you replace the distributor cap, replace the rotor as well. I can't imagine the rotor would be that difficult to remove. Like gtxrider said, the rotor either slips on/off or is held by 2 screws and they'll usually be on top of the rotor, not underneath.

Just my 2 cents..................

so..yeah.. the rotor can be VERY hard to get off. The shaft is slotted and a tab on the inside of the rotor fits into it so they turn as one unit. Since it is a pressfit, the spec calls for the rotor to be locktited on... which means its basically glued on. The manual says to put two screwdrivers under opposite sides of the rotor and pry it up... I found that warming up the rotor with a heatgun softens the locktite so it comes off easier, but be careful not to cook the electronics under the rotor...

[2Blackdogs]

In removing the filter, even the cap type remover may not fit right.

One of those giant 18" Channel-Lock pliers made in Taiwan will work wonders. They are also called water-pump pliers. Short of that, I saw a mechanic drive a screwdriver right through the filter at the cap area and unscrewed it that way. Messy, but effective.

I've used an anti-seize compound, but have also read that it is either unnecessary or undesirable.

Vapor lock is a possibility. Check that the gas lines don't come near any exhaust parts. Under very high heat circumstances, gasoline can boil inside the gas line, causing the problem you describe.

[gtxrider]

Originally Posted by 2Blackdogs

In removing the filter, even the cap type remover may not fit right.

One of those giant 18" Channel-Lock pliers made in Taiwan will work wonders. They are also called water-pump pliers. Short of that, I saw a mechanic drive a screwdriver right through the filter at the cap area and unscrewed it that way. Messy, but effective.

I've used an anti-seize compound, but have also read that it is either unnecessary or undesirable.

Vapor lock is a possibility. Check that the gas lines don't come near any exhaust parts. Under very high heat circumstances, gasoline can boil inside the gas line, causing the problem you describe.

USE Anti-seize on the plugs especially if the heads are aluminum also a bit of ignition grease on the plug wire boots. Keeps them from sticking and it is also water tight.

[Dave R]

While I think an ignition tuneup is a good idea, your problem sounds exactly like your inital diagnosis, fuel starvation. Approach it that way to start and then expand the diagnosis as necessary. Boat spark plugs last for hundreds of hours and don't typically fail so catastrophically.

You may need to fill the new fuel filter before installing it, many mercs won't draw enough fuel into the filter, to keep running, when it's installed dry.

You don't need another fuel filter downstream of the spin on filter, filter-wise (not water separation) it's probably got adequate filter media area for the lifetime of the engine. You only need to change it to get rid of water.

[TomC]

of this with his statement that the engines won't draw fuel.. Because of the balance shaft, which is necessary on the V6 even though it is basically a sawed-off V8, the fuel pump is not mechanically driven by the camshaft. Instead the V6 engines have an electric fuel pump which do fail from time to time. Unfortunately, this is an expensive part ($200).

there are some other twists to this too.. the power to the fuel pump is tied to the oil pressure switch to cut off fuel in the event of loss of oil pressure...

So you may ask: How does the engine ever start then (before oil pressure is developed)? Well, the fuel pump is energized by a separate circuit during engine start/crank..

So, Bigdog, besides all the other stuff that you are going to do/check - you might want to be sure that your fuel pump is properly powered and working.

I had a 1997 4.3L V6 that had a "soft" failure of the fuel pump - it wouldn't develop full pressure and it took awhile to fill the carburetor bowl.

[bigdog]

Update on the situation.....

I was finally able to remove the water-separating fuel filter with the new filter wrench, however in the process I 'destroyed' the filter ! You had to be the
'Hulk' to get that thing off ! I replaced last year, but don't remember putting on that tight ? Oh Well....

I dumped the contents of the filter into a glass jar, and it looks like all gasoline, couldn't see any water ? I did notice however, a great deal of sediment, which looked like 'pieces of rubber', as Chris Craft described.
I added gas back into the filter, and shook around then dumped again, and got more stuff out. Not much in all, about 8-10 little pieces. Would think that this would cause engine to stall, but maybe this is all that's needed ?

Yeah ‘Ethanol’! This stuff has caused more problems and money to boaters, than anyone could have imagined ! Thank the US Govt or pushing this agenda!

Going to purchase two new water-fuel filters, one to install and keep one as a spare. Will go through the process from the beginning to identify the main issue.

Could not check fuel pump at this time. If there were particles in the fuel-water filter, could those have passed through into, and plugged the fuel pump somehow ? Sorry I'm just not real familiar about fuel system and delivery to carb.

Thanks!

[John A. Birdsall]

I am not sure if it is because I have a 1979 Evinrude 115 hp outboard, but last fall and the fall before I put stabil in my tank and left it in the boat part full of gas. I took a fresh tank with me this year, started it on that and then switched back to the old tank, I ran it out and had no problem. I have yet knock on fiberglass, to have a problem with the "new" gas. Now motor mounts and lower units, yup have had problems with that, but that is not fuel connected.

[Chris Craft]

If you are VERY carefull you can open up the filter and actually look inside it to see how bad the problem is. DO NOT use electric tools. Just grab some tin snips and cut around the top. If you fins lots in the filter you HAVE to address the problem.

[Chris Craft]

Originally Posted by gtxrider

USE Anti-seize on the plugs especially if the heads are aluminum also a bit of ignition grease on the plug wire boots. Keeps them from sticking and it is also water tight.

You should NEVER use regular anti seize on plugs especially alluminum heads. It will accellerate the process of galvanic corrosion. We like to call it always seize. Merc does make some special goop for it. I have always just used the old white lithium paste.

[DTBC]

Does your engine have a carburetor or is it fuel injected. If it has a carburetor, have you ever had a tune up done on it with a new float and needle and seet (I am not sure if that is spelled correctly). I had an engine in the past with issues like that, got the kit that you can buy and it solved all the probelms. The float in the carburetor can get fuel logged (Absorbs fuel overtime) and be to heavy to function properly and the needle and seet won't work well also. If your mechanically inclined some, it can be done by yourself and what others have said, it is not that expensive to try. Good Luck.

[bigdog]

Well, here's the latest update......

I changed to water-separator filter wit a new one. As I previously stated, when I dumped the gas out from the old filter I noticed about a dozen little pieces of what looked like 'rubber pieces'. I did not dissect the old filter to inspect the inside closer.

I also changed out the spark plugs. Most looked pretty back, and had black char-like coating. I replaced all with new. FYI, one plug actually crumbled and broke in my socket wrench when removing, but thankfully, the head was still intact in the block and could be removed. Whew!
My engine placement and design makes it extremely difficult to perform many of the common maintenance tasks. You almost have to be a contortionist
to work on anything !

I started the engine, and with the new spark plugs noticed a huge difference, engine started almost immediately without a lot of cranking. Ran engine for about 15 min, even at half throttle without and hesitation. Purrrrrrred !

I also noticed some corrosion green-chalky buildup on the cables attached to the coil/ Removed all cable, steel-wooled then reattached and coated with electric battery spray lubricate. The coil, was one of those components
not easily reached. Battery cables all in good shape, and also treated with elect. spray.

Put about 5 gal. of fresh gas in tank. Started the engine and ran it for about 15 min. without and problems. I ran at idle, half and full throttle to test for any hesitation or gas starvation. ‘None’! Ran smooth through the whole cycle,

Off to the Lake, and ran boat about 10-15 min at about 15MPH, and dropped anchor for a swim and lunch. No problems noticed. Picked up anchor and headed to another location, this time I started to run at full throttle, and was running fine for a few minutes. Again, the engine started to sputter and cough, and I even think I heard some backfire. However, this time the engine did not stall. I slowed engine back down to about 10 MPH, boat smoothed out and continued to run. Headed back towards boat ramp. I figured if the boat was going to die, I wanted to be heading in the right direction! Went a couple miles, stopped engine, dropped anchor, and another swim.

Since it was getting late in the day, we decided to head home. Engine started right up,
no problems. Made it back to ramp at headway speed without issues.

Unfortunately, I still do have an issue, but not as bad as originally. I still think I have a 'bad gas' problem, and maybe after running awhile, and adding fresh gas the problem with be resolved?
Last summer the boat was running fine, so I have no reason to assume that I have a major issue?

If not a ‘gas issue’, I guess I could however, still have any one of a dozen problems, from fuel pump, ignition module, collapsed gas hose, or maybe just a bad carb.float and needle ?

BTW, if the carb. float was full of gas and sinking, wouldn't this cut off the gas like starvation ? Think I remember a car that had that problem.

Approaching things being simple first, what would be your best guess ?

Thanks!

[2Blackdogs]

Simplest would be to check the ceramic color of each of the new spark plugs.

More than likely it will be black again, which suggests an excess gas mixture from the carb. A sinking float will create an over-rich mixture, reducing your mileage. If not black, it could be water or an ignition fault. A single very light-(or black) colored plug may show an internal engine problem.

Is your gas tank made of fiberglass? If you still have the fuel filter handy, I'd take a look inside as suggested earlier.

That spark plug probably broke upon removal. Plugs are tough. Bosch once had advertisements showing their plug being hydraulically pushed through a steel plate.

[Chris Craft]

I would also check the fuel filter again for more particals. That one has me worried. Not sure in your boat but fuel line is fairly easy to replace in most, OR just the other day I had at my house one of those 5 gallon carry tanks. I looked inside it and there was like a molasses type goo in there and lots of black particals. I have NO idea were that came from.

Jon

[MJM]

~ I hear that the station next to IGA in Wolfeboro has Ethanol-free gas, and that they had a sign out front saying "Marine-friendly gas".

~ Is your gas tank stainless steel, or fiberglass? I've heard the ethanol can react with the fiberglass, causing all sorts of carb problems.

[bigdog]

Thanks for all the continued feedback. Always appreciated!!!!

Forgot to mention Merc 4.3L is a 1995, but only has 175 hrs.

My gas tank is a aluminum metal tank, holds 35 gals. If you do the math, my full tank has roughly $140. of gas in it, assuming $4 per gal. That's a lot of money to drain and toss ! BTW, how would you drain this amount, and what would you do with it anyway ?

Also, I forgot to say that when the engine began to sputter and cough
my wife noticed a 'very strong' odor of gas. She was sitting on the back bench seat, which is directly in front of the engine compartment.

That being said, I searched he 'Marine Doctor' website for such a condition.
http://www.themarinedoctor.com/cgi-bin//YaBB.pl
Free forum, and a wealth of information. Check it out !

Someone wrote in the following problem which describes my condition:
‘The engine works fine when cold and at low RPM. When the engine is warmed up, the engine feels like it isn't getting fuel, and will surge between high and low RPM and will sometimes stall out. It always restarts immediately.’

The Marine Doctor wrote back the following:
Sounds to me that your float valve inside your carb is not working properly. Sometimes they get a pin hole and fill up with gas and won't float up to shut off the entering gas. Other times it's just a matter of adjusting the tap that pushes the needle valve closed.

My thoughts were if the float was not shutting off the flow of gas, I would continue to fill the carb.and actually ‘flood it”, causing the symptoms I’ve described to the ‘tee’ ! This would also cause the plugs to look black, caused by the engine running too rich, as a result of all the gas being introduced.
Note: I have pulled plugs since replacing before my last water trip, so don’t know what they look like, just an assumption. Will pull a plug tomorrow and check.

Could it actually be something this simple ? And how difficult is this to change-out and install the float And adjust the ‘tap’ ? Do you need to remove the carb. for this maintenance, or is this something I should leave to a mechanic ?

Think I’m getting close to the problem. Have to keep thinking simple !

Thanks!

[robmac]

depending on the make of carb will tell rechnical difficuty of the job.If it's a holley style carb very easy(just did it Sat.at the track.Carter style more involved but can still be done on the motor.I would which ever the case remove it,keeps the chance of gas in the bilge minimal.parts can be purchased at most auto parts stores which helps control cost.

[bigdog]

Hi Folks,

Just wanted to give everyone the results of my original problem.

After several unsuccessful and frustrating attempts to resolve the problem myself, I finally brought to my marine mechanic.

Problem was identified as Carb. related.
He performed a carb rebuild kit, and all appears to be well again.
Carb had to be taken off engine, and carb kit installed,
Carb is a 4 bbl Holley. He said rebuild kit includes all usual parts: jets, float, needles, etc. He saved old parts for my review.

He also checked distributor and rotor, and fuel pump, all was ok.

Two hours of labor, plus carb kit parts. Figured I got away inexpensive. could have been more serious and expensive ! I think he actually did a lot of work for those two hours of labor.

Hopefully, all this aggravation is behind me.
Off to the Lake for some cruising.....

Thanks everyone for all the information, much appreciated !

Bigdog