surging at idle

[351 OMC]

Help! Have a 1994 351 ford omc efi. Just pulled head on port side to get a broken spark plug out and put it all back together. The book says to set idle at 600. If I set it at 600 it surges from 500 to 800. If I give it a little throttle, around 800 to 1000, it purrs just great. I have checked all hoses and pcv valves and connectors. Any suggestions? My wife says she remembered it doing this some at idle during the last part of the season in 06.

 

[Don S]

Re: surging at idle

What manual do you have?
First of all, you can't set the idle on an EFI engine. The computer (ECM) determines the idle. So if you tried setting something, you probably shouldn't have. What did you adjust?

 

[351 OMC]

Re: surging at idle

I guess I should say setting the idle with the throttle at 600, then moving it to 1000 with the throttle. But there is a little spring type knob on the side of the throttle housing (on the neck that goes to the flame suppressor)that I have moved around a little to try and get something to change. Do you know what would cause the surge if nothing has been changed? Is taking it to a shop with test equipment my best option or do you think I stand a chance finding the problem? I have a Chilton manuel that covers several engines.

 

[Reel Poor]

Re: surging at idle

If you don't have the equipment to check the computer control system take it to you favorite dealer.

BTW, Chilton manuals do not cover marine engines or their electrical control systems.

You need an OMC repair manual.