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mercruiser 5.0 efi low rpms

R

robori

New member
New fuel pump(cool fuel),full tune up,and replaced ignition sensor wich seemed to help a little. I can get rpms when in neutral but underload I get low rpms and if I push it to 4000 engine will knock a little and start to bog .I checked fuel pressure awhile back I'll check again soon.
Starting to wonder about going back to carb. Any ideas?
 
What year is it? How many engine hours? Have you checked the compression on a warm engine, dry and wet(teaspoon of engine oil per cylinder).
 
The engine is a 2000 mcm 5.0L efi ser.#0L610239 with 690 hrs. I've checked comp.when I first had issues(checked good at the time) and have not checked recently. Thanks for the reply.
 
Yes changed wires twice just to be sure, and it wouldn't hurt to have an extra set and replaced the coil. I'm thinking a bad sensor,but wich one? Time for me to bury my head in this new mercruiser book. I'm learning alot about these fuel injected engines cause I have to. Thank you for your reply and looking forward to more.
 
Ayuh,... How 'bout the fuel Filter,..??

If changed, was the Contents of the old 1 inspected for Crud, or water in it,..??
 
ya that was one of my first thoughts too,checked fuel pick up,checked contents of fuel filter all checked good.This has been a head scratcher for me.
 
check the vent line? run on aux. fuel tank with fresh fuel to verify fuel system?check dist. for carbon tracking, check see if knock sensor is loose?
 
Don`t know a thing about his boat or type of ignition system but an old codger like me automatically thinks timing when someone says the knock word?
 
plugs look great and has new cap a rotor. I think I might have to bring to a shop again.To much work has been keeping me away from the boat.
 
I looked up your engine and saw it has throttle body EFI. One of the injectors may be dirty or has a poor electrical connection. Remove the wire connector and inspect it for corrosion. Run some fuel injector cleaner through the water separator filter--dump out the gas and fill it w/injector cleaner then run the engine at 1500 RPMs on a hose/muffs on on the water at 3500 RPMs. My favorite cleaner is Seafoam. Merc. has their own brand of the same thing.
 
Lack of power and electrical injector issues have been popping up all summer long. Kghost had a thread the other day describing how he maintains his EFI boat--good information.
 
Everyone tells me how lucky I'am because I'am working so much, but it's not letting me work on the boat so I think I might bring it to the shop and let them get to it. I will post the resolved issue I hope. Thank you
 
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