Engine running very rough after warm-up. Eventually quits.

[laseron]

My 89 FJ has suddenly started to run rough, as if missing on one or more cylinders after warm-up. Starts up just fine, idles well. After I ride a mile or so, it begins stumbling and losing power. Eventually the engine quits, and will only start with choke on. I have Dyna coils in it, but otherwise it's stock. Original igniter box. The OEM fuel pump runs fine throughout.

Could the coils be affected by engine heat? Or do I have a fuel/carburation problem. Maybe the universe has decided that 96,000 miles is enough.

Ron

[FJ_Hooligan]

Sounds like classic symptom of bad tank venting.

[laseron]

I hadn't thought of that! I'll check it out. Thanks!!

[laseron]

Does the tank vent through the gas cap, or through the overflow tube at the rear of the tank?

[Pat Conlon]

The overflow tube is just for spillage in the recessed area around the gas cap. The tank is vented thru the gas cap.