Truck will start but will idle down and die


Asked by 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.


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


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.


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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