Rebuilt 91 omc 4.3 dying after few minutes runtime

[ncooper876]

I have a 91 4.3L OMC Cobra engine in an 18' Marada bowrider. I just replaced the engine a month ago with a rebuilt one from Rapido Marine. I also replaced: waterpump, pwsteering pump, thermostat, and new electric fuel pump. The engine runs great! I went out and after 10-15 min runtime it would slowly die sounding like it was not getting enough fuel...It is. If you pump the throttle, it will flood the engine after just a single pump. If you wait about 5 min after it dies, it will start right back up. It only seems to happen when running above idle for that amount of time. Never happened before with the old engine, and seems to be getting more frequent. I have been told either the coil or the "igniter" in the distributor have gone bad...neither of which anyone seemed to think was the real problem. I'm stumped and frustrated. Any ideas?

 

[lrlima]

Re: Rebuilt 91 omc 4.3 dying after few minutes runtime

Just a few guesses...Is the fuel pump pumping too much fuel i.e. is it different than the original oem type? Also, when was the last time the carb was redone? <br /><br />And...Welcome to iboats!

 

[ncooper876]

Re: Rebuilt 91 omc 4.3 dying after few minutes runtime

The old engine was a mechanical pump, the new engine came with this fuel pump. The carb was rebuilt 2yrs ago. Could that be it?

 

[Don S]

Re: Rebuilt 91 omc 4.3 dying after few minutes runtime

A couple of possibilities, <br />1. Plugged fuel tank vent line or fitting.<br />2. Air leak in fuel system starving the engine of gas at higher loads and rpm.

 

[searay3]

Re: Rebuilt 91 omc 4.3 dying after few minutes runtime

Coils can act real funny when they are failing. Sounds like classic coil failure symptoms. Heats up under load and fails. Cools off and works again until heated. It's a cheap part. Replace it with the proper type. Inside the distributor is another small coil that signals when the field is broken by the trigger plate when it rotates. I have never had a pickup coil go intermittent. When they fail, they fail. I would change the Hi Voltage coil and check the tank for proper venting etc....

 

[Bondo]

Re: Rebuilt 91 omc 4.3 dying after few minutes runtime

It should be Easy Enough to See whether it's Loosing Fire,... Or Fuel, when it Quits.......<br /><br />Why keep Throwing Parts at it...........

 

[boathog]

Re: Rebuilt 91 omc 4.3 dying after few minutes runtime

test run your boat useing a 6 gal tank (sounds like the pickup in the tank)