i need help figuring out this motor problem

[KingFisherWest]

1983 Penn Yan with a 3.8 GM V6 (OMC).

Now keep in mind this problem comes and goes, thats whats baffeling. It happens when running fast and trolling. Your going along and without warning the motor idels down until it shuts down. Then it takes anywhere from 10-30 mins to get it to restart. During restart you have to pump the throttle (in nutral of coarse) back and forth like a mad man to get it to catch and to keep it running. Sometimes it back fires when trying to restart. Once it finally starts and will idle without pumping the throttel or stalling out, you have to let it rev any where from 2000-3000 rpm unti it finally smoothes out. Then it may run for an hour wth no problem or for even 8-16 hours of run time before it happens again. Just so you know the distributer was convertsd to solid state (no more points and condenser).

I have had this problem since Aug '10 to present. This is very frustrating and keeps me from taking the boat places i know i dont have people i can call if i cant get it started.

Things tried to fix this problem:

1. Carb rebuilt

2. Many types of fuel additives

3. Fuel tank inspection for foreign particles and/or water

4. Fuel filters changed numerous times (filter at carb and canister filter)

5. Tank vent tubing checked for clog

6. New fuel pump put on

7. Checked to make sure fuel was going into carb from tank and during attempted start up while pumping throttel

8. Cap, rotor, plugs and wires changed

9. Checked to make sure spark was blue coming from coil

10. Use only gas from name brand stations (no reservation gas)

11. Use of ethenol eliminater with EVERY gallon of gas

[ray koziatek]

does it do it trollin in flat water or bumpy water specially when broad side to waves

[t2al]

It coud be vapor lock in the fuel systeme

[Ray]

Seeing what you have checked so far, I would consider vapor lock too.

[L&M]

I'll 3rd the vapor lock

[KingFisherWest]

how do i fix vapor lock

[KingFisherWest]

Ray K

It dont matter the lake condition or directio the boat is going

[rshubuck]

I forth the vapor lock! Open your gas cap on the tank and if she runs better then you know if it is vapor locking problem. If this is the case you have a blockage in the vent line on your gas tank. What is happening is your motor is pumping fuel out of the gas tank. As gas is being pumped out of the tank air is being pulled into the tank to fill the empty space. If there is a blockage or "restriction"on the air flow then the motor will not be able to pump the fuel and cause the motor to quite caused by the lack of fuel. The back firing is most likely the cause of pumping your throttle so much that your flooding the motor out. Hope this make sense. Please let us know how you make out. Good luck!

I think what Ray was getting at was a low fuel problem. The port that sucks gas in the tank must be sumerged in the fuel at all times or it will suck air and have similar issues. It may not be a low fuel problem if the port that sucks fuel is to short in the tank and not reaching to the bottom of the tank. If it is a rough out the fuel will be moving all around the tank allowing that port to suck air if this is the case. But it does not sound like it.

It really scarys me that I might be opperating on Ray K's brain wave length!

[L&M]

Vapor lock is a problem that mostly affects gasoline-fueled internal combustion engines.

It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, resulting in transient loss of power or complete stalling. Restarting the engine from this state may be difficult. The fuel can vaporise due to being heated by the engine, by the local climate or due to a lower boiling point at high altitude. In regions where higher volatility fuels are used during the winter to improve the starting of the engine, the use of "winter" fuels during the summer can cause vapor lock to occur more readily.

Vapor lock is not caused by a fuel venting problem. But by engine heat and/or temperature in general in the engine compartment vaporizing the fuel before it reaches the carb.. Hard restart & back firing is due to a very lean mixture until the fuel cools enough to return to a liquid state. Normally rerouting the fuel line between the pump & carburetor away from the engine block will cure the issue. The problem will also occur if the engine is running at a higher than normal operating temperature due to thermostat, impeller failure or another issue that would cause it to run on the high side.

[KingFisherWest]

Well if vapor locking is related to engine heat it may not be it. I have had times where it has happened at the dock within minutes of first start up. I have actually had it happen to where i cant start the boat at all with out going through the pumping of the throttle and taking up to 30 min to get it started. Prior to last Aug. it always started right away. I know its not a vent problem thats #5 on my list of things checked.

Thank you so much for your responses. Keep them coming

Dave

[Blue Heron]

a long time ago I had a boat that would behave in a very similar way - drove me nuts for about a month since there was not really a pattern of when it would act up - stranded me 3 times requiring me to get towed in - the original dealer was clueless .

I went to another marina and they quickly discovered that there was a ball check valve in the Gas Tank pick-up tube that was sticking - they simply removed the ball and the boat ran flawlessly from then on

Just a thought

[KingFisherWest]

thank u very much Ted i will check on that

[LongLine]

I believe there is a law that you must have an anti-siphon valve on your tank. Best to replace it rather than remove the ball. They're not inexpensive.

Tom B.

(LongLine)

[woody 184]

Hank could this problem with his boat possibly be a bad Coil.. When I my Penny I had a month of hell very similiar to the issues he is having... I thought I had water in the fuel so I kept replacing fuel filters and that was not it.. I was talking with a friend of mine who is a mechanic and he said its your coil.... I put a brand new coil in the boat and the problems went away and that boat purred like a baby kitten....... Woody

[56fish]

could very possibly be an IGNITION problem. check ALL the Ign. wires for corrosion, looseness, CK inside the cap under rotor, pick up coil? ign. module. ?? p/u coil usually is always NO START. moisture around connections. even tho it looks like u may have a decent spark. I,m not a boat tech, but many times on cars these little areas are overlooked. HAVE YOUR DISTRIBUTOR CHECKED BY A QUALIFIED SHOP.

JMO

[t2al]

usully a ignition problem the engine cut s out or (sputter)your s is dying off slowly? it must be fuel related.I woud put a see thrue in line gas filter near the carb if possible,that way you will be able to see if it s fuel starvation. Al