Mercrusier Engine Issue

[lazy grady]

10/16/22 I have a 2014 I/O Stern Drive on my 1994 24’ Grady White. (350 Mercrusier Mag EFI , with less than 100 hours). On two occasions the engine has cut off while at idle and then would not start. Starter would turn over. Some 15 to 30 minutes later after being towed in, it cranked and ran fine.

Gas/fuel quality is not an issue. The fuel filter is new. The sleeve from the tank fill cap to the fuel tank is new. The boat itself has been restored to like new condition (new electrical as to boat, not sure as to motor) but to my knowledge the electrical, fuel pump if applicable and gas lines on the engine are original (2014 or 1994)? The computer is new.

Thinking it maybe some kind of sensor on the engine that when the engine is hot, the engine will shut down at idle then not start? I note that the engine has never shut down while up and running? The other known issue is that when I attempted to install a new raw water wash down pump, the voltage at the pump was less than 12. The pump would not run. The fresh water pumps do not work, they are original (1994) as far as I know?

 

[DennisG01]

"Starter does not turn over"... that, coupled with the engine dieing... leads us towards main battery connections (both positive and ground). Check at battery (and at the starter fuse).

Not having 12V at the pump - gotta check electrical connections again.

But before you do all that... what's the condtion of the battery (ies)? What is the resting voltage, directly at the posts? Load test them.

Which computer is the engine using? Look at it for identification.

What is a "sleeve" from tank fill?

 

[lazy grady]

10/16/22 Thanks for responding. Starter DOES TIRN OVER. Sleeve is from gas fill cap to fuel tank. Your thoughts are appreciated.

 

[DennisG01]

What is a "sleeve"?

OK, so by "starter turns over"... does that mean the engine cranks but never attempts fire? Or does it make some noises like it's tryign to start but never fully does?

Computer?

What's the fuel pressure when trying to start?

It may be as simple as a clogged vent line - try with the fuel cap off. But how long did it "run fine" after the no start issue?

 

[lazy grady]

10/18/22 Thanks for responding. Sleeve is fuel line from fuel intake cap to tank. Engine cranks but never attempts to fire.

I am away from boat. I do not have computer info other than it was a factory purchased and installed new say a year ago.

Don’t know fuel pressure however a new fuel pressure module was installed say 6 months ago due to engine pausing. It fixed the problem.

Engine ran find after no start issue until I shut it off at the dock, say 15 minutes.

 

[seasick]

Sounds like vapor lock possibly but first you need to eliminate a no spark condition. That is fairly simple, just wait for the problem to occur and then test for spark.