Will not start

Tiny
TIM.BAISDEN
  • MEMBER
  • 1994 FORD F-150
  • 4.9L
  • V6
  • 4WD
  • MANUAL
  • 139,000 MILES
My truck will not start unless you use starting fluid in it. The when it starts it has a rough idle and you try and give it gas it dies off and the fuel pump stays on all the time the key is on.

Please help
Monday, June 20th, 2016 AT 10:27 AM

7 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Your first step is to use a fuel pressure gauge and check it against the spec.
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Monday, June 20th, 2016 AT 11:10 AM
Tiny
RENEE L
  • ADMIN
  • 1,260 POSTS
Hi Tim,

Here is a link to an article from this site that features written instructions and pictures showing and explaining the process of checking the fuel pressure yourself. If you decide you would like do this yourself you can purchase a fuel pressure gauge online from sites like Amazon.com.

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

Thank you for visiting 2CarPros.

Kindest regards,

Renee
Admin
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Monday, June 20th, 2016 AT 11:14 AM
Tiny
TIM.BAISDEN
  • MEMBER
  • 5 POSTS
Thanks I will check this and see if it fixes it. But would this make the fuel pump kick on and stay on the whole time the key is on
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Monday, June 20th, 2016 AT 11:22 AM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I agree with my colleagues.
Initial prime, key on engine off, the pump should only run for couple seconds, w/o rpm signal. The computer grounds the coil side of fuel pump relay. There could be other issues. You need to do some testing.
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Monday, June 20th, 2016 AT 11:44 AM
Tiny
RENEE L
  • ADMIN
  • 1,260 POSTS
Hi again Tim,

Sounds like your fuel pump relay is stuck. Please locate your fuel pump relay in your power distribution center and replace with new. Did you know you can purchase the relay online from sites like Amazon.com?

Here is how you can test your relay.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If you need further help please come back to 2CarPros as we are always happy to help.

Kindest regards,

Renee
Admin
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Tuesday, June 21st, 2016 AT 6:40 PM
Tiny
TIM.BAISDEN
  • MEMBER
  • 5 POSTS
I checked the fuel pump relay and it was good and I changed the throttle body gasket and it fixed pretty well everything but it is still flooding itself and it dies and is hard to get started back and the fuel pump is still running the whole time the key is on.
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Monday, June 27th, 2016 AT 10:35 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hey Tim,

This sounds like the computer is having problems becasue the fuel pump trigger is driven by the computer.

Please let us know happens so it will help others.

Best, Ken
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Monday, December 19th, 2016 AT 11:35 AM

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