Mercrusier 5.0 EFI Accelerates By itself

[synergy141]

Hi, I have a problem with my 2002 Mercruiser 5.0 EFI engine. The motor accelerates by itself randomly. For Example, I could be cruising at 3500 RPM then all of a sudden without touching the throttle it will accelerate to 4000rpm for 2 seconds then drops back down to 3500rpm, then 10 seconds later it will do it again. Then sometimes if I keep it at 3700rpm it will run normal. Where should I start?

 

[boat127]

Re: Mercrusier 5.0 EFI Accelerates By itself

do you have a serial # for you engine? surging at higher rpms usually is a fuel restriction. start at the tanks and check every line, fitting, elbow, etc.
check the antisiphon valve it could be stickin its right on the tank pick up with the fuel line is. and check the tank vent.

 

[Dshow]

Re: Mercrusier 5.0 EFI Accelerates By itself

Also, a scan tool would be helpful to see if there are any fault codes and the sensors are reading correctly.