Fuel in the air cleaner

Asked by mpqualdie Mar 08, 2019 at 10:32 AM about the 1978 Ford F-250

Question type: Maintenance & Repair

I have a 1978 Ford F250 with a 351 Modified engine. I has the engine rebuilt
professionally a year ago (about 6k miles).  Recently, it started running rough
and backfiring when accelerating hard. I changed the whole ignition system
including installation of an HEI distributor, plugs, wires. It runs stronger, but
still not right, like it's only running on 7 cylinders and still backfires when
accelerating hard.  I set the floats in the Edelbrock carb and adjusted the
jets, and again, it runs better, but still weak and backfires on acceleration.  I
noticed yesterday that the air cleaner was soaked with raw fuel and then
noticed it appears that it is spraying fuel mist out of the top of the carb rather
than sucking it in.   Any ideas, because I'm running out of them quickly and I
hate to think something has failed in the motor...

2 Answers


Sounds like a bad intake valve, locate the cylinder that's missing and do either a compression test or a leak down test to confirm it. I hope this helps. Take care.

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