How do I fix a slow fuel pump


Asked by Aug 19, 2015 at 05:06 PM about the 1991 Ford F-150 STD LB

Question type: Maintenance & Repair

My 1991 F-150 pickup won't start until the pump runs for 5-10 minutes and builds up
pressure enough.  It this the pump or something else?

3 Answers


Sound like the fuel pressure regulator or possibly a partially clogged fuel filter but more than likely it is the regulator.

Tom Harmon

If it's the original pump then it's probably near the end of it's working life. Imagine if you had a daughter when you bought the truck, then you would more than likely be a Grandparent today


Get a gauge and check the pressure being delivered to the regulator. Key on, engine off. Note the pressure when you initially turn the key to the on position. If it takes a while to build up pressure to spec, suspect a clogged filter or bad pump. If you suspect a regulator problem remember the regular is a mechanical device, not electric or electronic. It, by itself, does not send OBD codes, but could affect things like oxygen sensors readings which could throw a code.

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