bad fuel pump?
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New User
Joined: Jan 2003
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bad fuel pump?
what does a bad fuel pump act like? it is a really old pump and recently ive had problems keeping my truck running. its a 72 f250 with a 390. it runs fine for a bit but then it will start running very bad and i cant barely keep it going. the rpms will fluxuate even with a steady foot on the pedal.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
bad fuel pump?
The only real way is to put a pressure gage in line and see what it's doing.
As for testing them.....If you can crank it long enough, take the line off carb and put in empty can. Crank for a few moments and see if you get constant fuel coming.
Sometimes the diaphram will break and you will notice oil/fuel leaking from the weep hole in the side of the pump.
Sounds like the valves are not staying closed and it is letting fuel bleed back down line when diaphram is returning. Make sure you have NO obstructions in tank, like the pickup screen/sock. Make sure your rubber lines are still stiff. They like to shrink shut under vacuum when they get old.
Does your pump have the filter hanging on bottom?? Remove element and see if that helps. May be clogged shut.
Just some ideas.....
Larry
As for testing them.....If you can crank it long enough, take the line off carb and put in empty can. Crank for a few moments and see if you get constant fuel coming.
Sometimes the diaphram will break and you will notice oil/fuel leaking from the weep hole in the side of the pump.
Sounds like the valves are not staying closed and it is letting fuel bleed back down line when diaphram is returning. Make sure you have NO obstructions in tank, like the pickup screen/sock. Make sure your rubber lines are still stiff. They like to shrink shut under vacuum when they get old.
Does your pump have the filter hanging on bottom?? Remove element and see if that helps. May be clogged shut.
Just some ideas.....
Larry
