Boating Blues
 

Here it is, the weekend following Memorial Day weekend, and my boat is still on its trailer parked next to my garage!

It's not from lack of wanna so much as it's a lack of being able to ensure my powertrain is going to run properly.

At the end of last season my boat started having problems, in this case the engine would die after I got on plane. It was just like someone shut off the key or closed the fuel petcock. It would restart just fine, but would keep dying about 30 seconds to a minute after being on plane.

Turns out the problem was two-fold: a partially clogged filter at the carburetor fuel inlet and a funky fuel line that was a bit squishy when I checked it. Both were replaced this spring.

Now that the first problem is fixed (I hope), a second has reared its ugly head - rough idle. I think either my son or I accidentally changed the setting on the idle mixture screw so now it's running a bit rich.

Do you think I could find out the correct setting for the idle mixture anywhere? Nope. Not in my manual(s), not online, and so far, not in any of the Volvo Penta forums. I can find the adjustments for the engine/outdrive combinations prior to and after my 1993 powertrain, but not for mine. Nosiree!! But I'm still looking....:(

Normally I have our boat in the water during the week prior to Memorial Day weekend. Not this year, though.

Is it any wonder I've got those boating blues?

Have you cleaned out the throttle body with TB cleaner?

What about the fuel pump? Get a gauge on it to see if fuel pressure is dropping out at higher RPMs. You can do this right on the trailer.

Worst case if take off the carb and have someone soak it in a parts cleaner. From your description it's fuel related (not air).

Does it die with load or just by RPM? Second question is does it have a rev limiter?

If it dies under load I'd check fuel pressure. Sounds like a dying fuel pump.....

Edit: Don't feel bad, I am traveling a ton and won't get to use my boat much this summer. On Monday I go back over the pond:(

...rule of thumb for idle adjustment(s) screws is usually: turn screw full in, then counter-clockwise 2 1/2 turns and you should be close...adjust from there...ALSO...if you have a water/filter seperator, change it out and check the old one for water...todays gas is causing water and fuel line degradation problems...did you check the "junk" in the old filter.?.."rubbery type" residues means gas lines need updating for the fuels today...if ok...LP's advise on fuel pressure is right on...BUT...I have had a coil "go Bad" on the high rpm side and the motor did exactly what yours is/was doing...good luck matey.!..:D...

In line filter
 

There is a filter in the fuel line just before the carburetor. I would definitely check that. My mechanic says 90% of fuel problems that came into the shop was at the filter.

Dying under load certainly sounds like fuel starvation. Once you get to using up all the gas in the fuel bowl it dies. Maybe dirt in the main jet, float bowl could be leaky and sunk, water in either the tank or the fuel bowl, water in the filter as mentioned. Another thing to check is your coil. it could be going bad. Once it heats up it will break it's internal connection and shut off. Then it cools enough to restart. Check your oil level. If once you get on plain the oil pressure drops, some engine systems will shut down the engine to prevent damage.
Not sure what boat and year you have.
Just thoughts.....:D

If none of the above works out the problem then it is possible you have some unwanted material in the fuel tank. I had a car that was doing exactly the same thing and after fuel pumps and filters, etc we found it had leaves in the gas tank. Good luck.

Don't have any help for you on the initial setting for the fuel and it sounds like you may have fixed the fuel starvation issue.

If you are still having trouble with fuel starvation you might check the check valve for the fuel vent line is working properly and that the vent hose is running straight from the side of the hull to the tank, is not kinked and does not have a low spot where fuel may accumulate and cause a venting issue. Also that the vent on the side of the hull is not plugged.

Hope you get it straightened out. :)

We had a similar problem and it was Ethanol gunking up the engine. Had the carb removed and cleaned and it purrs. (other mechanics said it was fuel line, starter, pump, etc.)

If everything is running fine now and it's just a matter of turning your idle screw, why not just run the engine and make the adjustment?

Also suggest using "Stabalize" or some other fuel additive on regular basis and if possible, disconnect fuel line and run engine dry after each use. (advice given based on experience)

This my friends is the problem. ETHANOL It works well enough in your car that is used every day. With boats, that are stored for six months at a time...no go. Ethanol seperates from the gas and turns everything..to GOO.

The ONLY solution is to Stabilize the gas beforehand (I use StarTron) which ..."may help"..but not guaranteed. If your engine is acting up or not wanting to run at all...carberetter overhaul will be required to remove the GOO. Not cheap, and will be required every time you turn around. Stupid gas is Stupid gas. Just sayin.:D :D

Write your Rep... Yeh Yeh... NB

Once you have a fouled fuel system it can be multiple items that need attention. Start simple and work up. Start with carb and throttle body cleaner and drain the carb. If you still have rough idle then you can just remove the carb and have a shop dump it in a parts cleaner and then blow it out. Using a couple sprays of starting fluid at the air inlet to help get the first start. If that fails you can go for rebuild. A flush of the fuel line would not hurt either as you may have crud in their as well.

If you have an in-tank fuel pump there is usually a "sock" filter on the fuel pump and if that gets plugged it could result in poor idle. On my Four Winns the fuel pump sits on the front of the motor (5.7L) and then has the in-line filter. I don't know what is down in the tank itself but you can call the dealership and they can probably tell you if it's just a suction line or more than some kind of basic screen.

Unless you actively turned the idle screw it's unlikely it turned on its own. Don't mess with it is my recommendation.

Bad plugs typically result in poor/hard starting, not bad idle. Bad coil/distributor typically results in missing/backfire and have a "you know it when you hear it" sound. So far you've not described either.

I use the Sta-Bil product as it has fuel system cleaner as well as corrosion inhibitors. I'd recommend pouring a bottle in your gas tank (certainly won't hurt).

There is no setting that works on all engines. Idle mixture is pretty much set by ear. You have to get the timing and idle speed correct, then adjust the idle mixture until it's too lean (screw clockwise) ans stumbles, then richen it up (screw counter clockwise) a smidge, until it smoothes out. If the adjustment was big, you may need to reset the idle speed and timing again.

That said, if you are using the idle mixture to compensate for another problem, it can get frustrating pretty quickly. Make sure the engine has good plugs, wires, cap, rotor; has no vacuum leaks, and has a fresh supply of clean fuel. Also, make sure the choke is operating properly, a stuck choke will cause a rich mixture too.

If you've done all that, and it still idles poorly, it's probably time for a carb rebuild. It's not hard, but you need compressed air, carb cleaner, and very fine wire (to "floss" the gunk out of the smaller fuel openings) to do it right. Great excuse for an air compressor if you don't already have one... IF you do opt to rebuild the carb, be aware that carburetor screws often stick a bit due to the dissimilar metals used in the screws and the carb body. A dab of valve grinding compound (auto parts stores sell it in a toothpaste-style tube on the Permatex rack) on the phillips head screwdriver tip helps prevent the screw driver from stripping the screw heads.

Boating Blues
 

Had a similiar problem,which sounded like fuel starvation, as you are having.

Engine would die under a load ! The marine tech I was using at the time
(he turned out to be just a 'parts changer', and never really did diagnosis), starting replacing parts, first fuel filters, rebuilt carb ($275), then replaced fuel pump ($125). Al these never resolved the problem.

It was only through Winnie 'boating' fourm, where eveyone gave me their feedback, where I was able to determine through my onw analysis, the the underlying culprit to the problem was a 'bad coil' ! Ordered the part myself for $40, and installed myself, alst June 2010. Problem resolved, and hasn't resurfaced so far, knock on wood !

You may want to check coil, before you start sinking big buck into a fix. Also, get a marine tech who diagnosis the problem, rather that remove and replace parts, to see if probllem goes away, through process of elimination !

Good luck !

Bigdog