My tub is a 93 Sunbird w/Ford 302 HO V8 with Petronix ignition. I've been chasing an intermittent rough idle /rich mixture problem. I've adjusted the choke, checked the plugs, fuel filters and fuel quality, also the mech. fuel pump seems to be working. The exhaust flappers are still there and in good shape. The ESA is working also. From threads I've read here, I'm going to rebuild the Holley carb next, to eliminate the possibility of the bowl sticking. Anyway last night I decided to check spark. I pulled each plug wire one at a time and while I have spark at every cylinder, the spark is yellow and seems kind of weak to me from what it should be, so I grabbed my timing light and figured let me see where its set at. Interestingly, my timing light would not light up, no matter what cylinder I connected it to. Figured my light was busted, so I tried it on my car and it worked. Now I'm thinking my problem is I have weak spark getting to the cylinders, too weak to trigger the timing light. I haven't timed an engine with a timing light in a long time, is it possible a weak spark would cause the timing light not to work? Any ideas appreciated. BTW I have owned this boat for five years, and it has run strong and smooth up till now. The only thing I have needed to do to it other than usual maintenance items is change the assist solenoid the beginning of this year, but I don't think that would be causing rough idle issues.
