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General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: laseron on August 17, 2018, 09:33:13 AM

Title: Engine running very rough after warm-up. Eventually quits.
Post by: laseron on August 17, 2018, 09:33:13 AM
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 :Facepalm:
Title: Re: Engine running very rough after warm-up. Eventually quits.
Post by: FJ_Hooligan on August 17, 2018, 12:53:23 PM
Sounds like classic symptom of bad tank venting.
Title: Re: Engine running very rough after warm-up. Eventually quits.
Post by: laseron on August 17, 2018, 01:29:53 PM
I hadn't thought of that! I'll check it out. Thanks!!
Title: Re: Engine running very rough after warm-up. Eventually quits.
Post by: laseron on August 17, 2018, 01:57:01 PM
Does the tank vent through the gas cap, or through the overflow tube at the rear of the tank?
Title: Re: Engine running very rough after warm-up. Eventually quits.
Post by: Pat Conlon on August 17, 2018, 02:06:32 PM
The overflow tube is just for spillage in the recessed area around the gas cap. The tank is vented thru the gas cap.
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