4.3L Will run for 30 seconds and die

[BBart]

I have a 93 Four Winns with a OMC Cobra 4.3L. After sitting for a couple days the boat will start and run for about 30 seconds and die. The first time this happened I poured gas in the carborator and it started right up. Ran fine all day. The second time it happened I pulled the fuel filter off put some gas in a small container and held it up to the fuel filter take-up tube turned it over and the fuel pump drew up the fuel and it started. Put the fuel filter back and it ran all day. The third time this happened I lossened the fuel filter turned it over it started tightened the fuel filter and it ran all day. Is this a fuel pump problem?

 

[cbucner]

Re: 4.3L Will run for 30 seconds and die

I will check choke assy first, run it with the air cleaner off the carb, and check if the choke opens up after 30 secs , it may stay closed and the engine dies.
Second check your fuel pump pressure.Go to an auto parts store and get a fuel pressure test gauge.It may bolt right up in between your fuel line coming from the fuel pump and carb but it may not so you will have to look for some fitting at your local hardware store to make it fit.If you have a mechanical pump 4-6 PSI should be good.
Also check all your filters from the tank to the carb.And don't forget the gas tank vent, make sure it's open and not clogged.
Good luck!

 

[180shabah]

Re: 4.3L Will run for 30 seconds and die

Check your anti siphon valve. Guess what it prevents?

 

[freddyray21]

Re: 4.3L Will run for 30 seconds and die

Check your anti siphon valve. Guess what it prevents?

genius

 

[thrasher]

Re: 4.3L Will run for 30 seconds and die

I give in, what does it prevent??

Just kidding..

Gary

 

[whywhyzed]

Re: 4.3L Will run for 30 seconds and die

Your Auntie Siphon from coming down and stealing your gas .... I'm dead serious

 

[BBart]

Re: 4.3L Will run for 30 seconds and die

I talked to my mechanic today and he said he has seen this problem before and is caused by the following. When the engine is shut down after running the engine compartment get hot enough to vaporize the fuel and push it back down past the electric fuel pump. Fuel pump looses its prime and can?t re prime itself. He also said fuel with alcohol in it will vaporize at a lower temperature causing this to happen more often. Like I said earlier it never happens once the boat is running. I can run all day without a problem. It only happens after it sits for a few hours. I will replace the anti siphon valve just to make sure that?s not the problem.

 

[180shabah]

Re: 4.3L Will run for 30 seconds and die

Your Auntie Siphon from coming down and stealing your gas .... I'm dead serious

 

[180shabah]

Re: 4.3L Will run for 30 seconds and die

I talked to my mechanic today and he said he has seen this problem before and is caused by the following. When the engine is shut down after running the engine compartment get hot enough to vaporize the fuel and push it back down past the electric fuel pump. Fuel pump looses its prime and can?t re prime itself. He also said fuel with alcohol in it will vaporize at a lower temperature causing this to happen more often. Like I said earlier it never happens once the boat is running. I can run all day without a problem. It only happens after it sits for a few hours. I will replace the anti siphon valve just to make sure that?s not the problem.

First your fuel pump is self priming, however it is only powered while the starter is engaged or the engine is actually running, so if it loses it's prime this set up makes it hard to reprime. unless you let the starter crank and crank until the fuel bowl in the carb is full again. Not recommended.

Second, if your antisiphon valve is not stuck open, the fuel cannot be pushed back down.

Third, after you replace the valve, before you try to start the engine, use a jumper wire to run the pump for 30 seconds or so. You will be able to hear the bubbles in the fuel line, when there are no more bubbles, plug the pump back into the harness, pump the throttle and hit the starter.

 

[BBart]

Re: 4.3L Will run for 30 seconds and die

I know the fuel pump will self prime up to a point.
Here is what else the mechanic. They were stumped by this problem and did the following (not on my boat but the same model). Put a clear tube on the intake before the fuel filter. Ran the boat in a tank letting it get up to temperature. Had a temperature gage inside the dog house. Shut the motor down and watched to see what happened. He said the temperature inside the dog house got to 180 degrees and over time (hour or hour and a half) they had air in the clear line. I asked him about the anti-siphon valve and shouldn?t it prevent the fuel from being push bank into the tank. He said it should but this is what they saw and there was nothing wrong with the anti-siphon. He said to go ahead and replace my anti-siphon valve but didn?t think that would solve the problem. He said the best thing to do is after shutting down raise the dog house and try and cool down the engine.

 

[whywhyzed]

Re: 4.3L Will run for 30 seconds and die

I talked to my mechanic today and he said he has seen this problem before and is caused by the following. When the engine is shut down after running the engine compartment get hot enough to vaporize the fuel and push it back down past the electric fuel pump. Fuel pump looses its prime and can?t re prime itself. He also said fuel with alcohol in it will vaporize at a lower temperature causing this to happen more often. Like I said earlier it never happens once the boat is running. I can run all day without a problem. It only happens after it sits for a few hours. I will replace the anti siphon valve just to make sure that?s not the problem.

If your engine's getting that hot in 30 seconds you got big problems...