View Full Version : MarinePower 8.1 EFI just stops running

Drifter II
08-23-2011, 11:46 AM
The engine starts fine when cold but just stops after it gets warmed up - temp guage is normal and the fuel pump clicks as normal but it will not restart - it will fire with a squirt of ether but will not start again until cold....could there be a defective safety switch or ?? - the boat is a very nice Gibson houseboat that belongs to a dockmate....

Jersey Devil
08-23-2011, 01:11 PM
I have Marine Power 454's and there is a built in safety feature that will shut down engine if it overheats. I know you said temp gauge reads normal but maybe the manifold temperature switch is bad and shutting down the engine until it is completely cool.

Brett Belec
08-23-2011, 03:49 PM
Could be Vapor locking....

Jersey Devil
08-23-2011, 04:29 PM
Does it not restart after you shut it off and then try to restart or does it cut off while running? If it won't restart after shutting off and it's hot then I would say vapor lock. I had same problem with my 454's and narrowed it down to the fuel line feeding the generator. Does this boat have a generator? Also, if it happens again try removing the gas caps and let the vapors escape and then try to restart. This seem to work for me until I installed a fuel cut-off valve on the generator fuel line or made sure that the fuel line was full of gas. It seems that when the generator fuel line was not pressurized vapor would flow back to the tank when hot and cause engines to not re-start. ( This assumes you have one tank for both engines and generator)

08-23-2011, 06:54 PM
What you need to do is get a fuel pressure gauge attach it to your engine and check the pressure while it is running, leave it running and see what the pressure reads when it dies.

Drifter II
08-24-2011, 10:32 AM
Thanks - that sounds like the right next step - is there a valve somewhere in the fuel system to hook up the guage?

08-24-2011, 06:20 PM
Is this a Multi port engine or TBI?

Drifter II
08-24-2011, 06:31 PM
Thanks for responding - the boat came without a manual for the engine but it's a 2002 Gibson with a MarinePower 8.1 vortec.....I am not near the marina but my friend says he changed the fuel filter today (refilled w/fuel) and now the engine will not fire at all....

Drifter II
08-31-2011, 05:32 PM
turns out it was the crankshaft sensor - a common problem on the early 8.1's - there was a recall as well....not hard to get to in a marine engine and at $60 - a cheap fix....