running rough
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Freshman User
Joined: Jan 2002
Posts: 26
Likes: 0
From: Deerfield, NH
running rough
I have an 86 F-150 with a 351M and a points distributor. The truck always ran well until recently. Now it backfires and idles roughly if at all. I replaced the points and condensor but no improvement. The engine is supposed to be from a 78 F-250 and the distributor is anybody's guess where it came from. Does anyone have any suggestions how to diagnose the problem or should I just go for an aftermarket electronic distributor? Thanks for any help!
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Joined: Jan 2001
Posts: 56,966
Likes: 2,728
From: Virginia
With the engine running carefully look down the carb throat. Do you see any liquid fuel dripping? If so, your float needle may have dirt in it. I am looking at the carb possibly being the problem because the running rough and backfiring may be caused by excessive fuel being dumped into the engine. There is also the chance the power valve has a hole in it, causing it to run rich, but it usually doesn't backfire because of this.
