Intermittent hard to start

KPADGET

MEMBER
2001 FORD F-150
4.6L
V8
4WD
AUTOMATIC
42,200 MILES

Engine has always started. May have this problem once a week. Suspecting fuel pump. Turn key on pressure goes to 10 PSI. Is this high enough? Then shortly drops back to 0 psi after pumps shuts off. When running pressure is 28-29 PSI. Pressure goes back to 0 PSI shortly after engine is shut off. Should it hold pressure for a while after engine is shut off? I have already changed pressure regulator.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

You found the issue. With the key on and the engine off, you should have between 35-45 PSI.

I suspect this is a pump issue but it could be a leaking injector as well. However, if the injector is leaking then you would normally have black smoke as well.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.youtube.com/watch?v=D1AyqeftAmA

If it were me, I would put the fuel pump in it based on this info as long as there isn't anything else that was left out.

Below is the process from the manual that will help with this. Let us know what questions you have. Thanks

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