Performance problems

[cwbdlb]

My mechanic just placed a through hull water intake and did maintenance on the outdrive. Said the first sea trial went well but on the second trial the following day the engine was not running well. Said it was loosing power so they’d have to pump the throttle to get it back up to speed. Felt that the carburetor needed repair and wanted ok to remove and work on it-$200 or so for the job. So beside the glaringly obvious first concern—my ‘02 5.7 L EFI mercruiser doesn’t HAVE a carburetor to repair what may be the cause of it loosing power at times? Any thoughts? I’m waiting to go out on it with the mechanic when they arrive at the marina to see how it runs myself but any thoughts other than finding a new mechanic?

 

[bobeast]

I think you're on the right tack in seeing for yourself. I can't imagine how "pumping the throttle" would have any affect on an EFI unless you have a clogged injector or two. Defiantly drop the word "my" from "my mechanic".

 

[CliffA]

could be fuel or ignition related.....I would not allow the 'mechanic' to make any repairs until he has done some diagnostic work to determine what the problem actually is...it can get very expensive quickly if you just start throwing money at it replacing parts until you get lucky and replace the right one....

good luck...and welcome to CSR....

cliff

 

[cwbdlb]

Tks. Anyone know where schrader valve is to check fuel pump pressure?

 

[Espos4]

It is on the fuel rail, top center of the motor, right behind the throttle body.............(not the carburetor)

How many hours on the motor? The distributor cap and rotor may need to be replaced if it hasn't been done in a while.

I had a high rpm misfire late last year, max rpm was down around 4,000 instead of the usual 4,600. New cap and rotor cured it.

 

[scoflaw]

Could be many things. When was the last full tune up ? I'd start there and see what the fuel pressure is doing when it bogs down.

 

[PlayDate]

Start with the fuel pressure and go from there. Could be a problem with the pump or the regulator. If the pressure is low or drops under load.....the injectors can't provide enough fuel to the engine which sounds like what you may be experiencing.

It probably goes without saying but be careful with the fuel pressure gauge and a running engine. 40+ psi of fuel pressure can spray a hot engine in seconds.

Also, when were the water separator and fuel filter last changed?