Erratic RPMs on 1 GM

[Jeff G]

I've got a 1 GM in my 25D that surges between 2000 and 2800 RPMs while at full throttle. The engine doesn't stall just surges. I have removed the fuel tank, cleaned it, and filled with clean fuel. I replaced all fuel filters and added a vacuum gage to monitor the state of the filter. The air filter is clean and there is plenty of air getting below. I can't seem to cure the problem. Anyone have any idea what might be causing the problem. Could it be the fuel injector?

[seadawg]

Good Morning Jeff, Did you bleed the fuel system all the way to the injector? Does the engine surge at lower levels of throttle? Is the fuel pump delivering fuel to the secondary filter mounted aft on engine? Installing a new injector isn't that big of a deal and not that expensive just for troubleshooting and it doesn't hurt to have an extra anyway. Just some thoughts, Cheers, Charlie

[seadawg]

Also did this recently become a problem or has it been going on for a long time. Cheers, Charlie.

[Jeff G]

I've had this problem for about 3 years. Previously, I just thought it was a fuel filter clog causing some kind of restriction. I've only bled to the secondary filter but now that you mention it I should check that out too.

[seadawg]

Jeff, let us know how it works out. It probably won't fix the problem but it might. It is just the next step in troubleshooting. If it were me I would install a new fuel pump just to eliminate it from being the problem. They are not very expensive and it is easier than trying to test for fuel quantity delivery. Still probably won't fix the problem just the troubleshooting process. Do you have a manual that tells how to bleed the injecter? Cheers. Charlie.

[Jim Davis]

Do a very critical eyeball inspection of every hose and connection looking for air leakage. Even the smallest leak can cause the problem. Perhaps clean the hoses with windex, 409, Fantastic dry and inspect the next day. This can be very frustrating, but ..........