Truck will start but will idle down and die


Asked by MrMSewell Jan 16, 2016 at 05:57 PM about the 1975 Ford F-100

Question type: Maintenance & Repair

I have a 1975 F100 Ranger XLT Supercab.  It has a 302 with 2 barrel carburetor on it.  I just rebuilt the carb and replaced the mechanical fuel pump and bypassed the electric fuel pump some guy had on it.  Fuel filter is clean.  I can turn it over no problem, but it will run for about 3 seconds and will idle down and die.  If I hit the gas pedal it will run but will again try to die when I let off.  I can not see any vacuum leaks.  Any ideas?

4 Answers


Spray a can of carburetor cleaner into carb not only cleans carburetor but also intake and cylinders and cleans valves. Also check air filter and replace if necessary.

1 people found this helpful.

Sounds like the carb isn't setup correctly. Try adjust the air screws in the carb base, I have usually started by turning them all the way in then backing out 2.5 turns as a starting point. HTH

1 people found this helpful.

A week ago I had it running perfectly. I could start it and run it for twenty minutes no problem. Then I put a bunch of gas in the gas tanks and tried running it and that was when this problem started. So I bypassed the electric fuel pump, replaced the mechanical pump and have clean brand new gas feeding directly from a clean brand new gas can into the mechanical fuel pump. That didn't help for long. After it started acting up again, I adjusted the idle control screw because I thought it might be idling too low but that didn't help either.

2 people found this helpful.

Found a problem. The brand new fuel filter leaks like a sieve. Otherwise it ran fine when I was working on it yesterday, until I tried to put it in reverse. But gave it a little gas and it went just fine. Thanks for the help!

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