1989 Ford F-350 no power to fuel pump

Tiny
BHERBIN
  • MEMBER
  • 1989 FORD F-350
  • 7.5L
  • 4WD
  • AUTOMATIC
I have no power going to my fuel pump. A couple weeks ago my truck kept dieing I thought it was the fuel pump so I replaced both the high and low pressure fuel pump but now have no power going to pump. I have checked the eec and fuel pump relay have a constant 12v at yellow wire and 4.5v on red wire. I have checked the inertia switch and its not popped. All my fuses are good. I am about ready to just blow it up. So to begin with my truck ran out of gas I put gas in it and then it started acting funny, it would die then start right back up so I thought it might be a clogged filter so that was the first thing I replaced. That had no affect so I thought the fuel pump might be going out so I changed the high pressure one first. The truck ran fine for a day then when I went to start it the next day nothing so I again changed the high pressure pump thinking I just got a faulty one, but no same problem. OK so I have just swapped out the inertia switch still no results. The truck is m7.5 L 460 motor. The back tank is not hooked up. There is no power to the inertia switch and no power to the pump. Please help
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Monday, February 16th, 2015 AT 8:24 AM

5 Replies

Tiny
HMAC300
  • EXPERT
Check the brown wire that goes to the inertia switch then see if inertia switch has power on both sides it could be just a bad switch. It could also be a bad relay as well. If no power coming out of brown wire at relay try replacing it with a like relay and see if it works. It can also be a bad ground on fuel pump. I am assuming this has dual tanks so it could also be the tanks switch I am sending that along on how to check for that.

LH Side Of Engine Compartment, On Relay Bracket. Fuel pump relay is next to the EEC Relay.

Applicable to: 7.5L/V8-460

Check out the diagrams (Below). Please let us know what you find.

Cheers
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Monday, February 16th, 2015 AT 8:45 AM
Tiny
BHERBIN
  • MEMBER
There is only a red and a black wire coming out of the inertia switch
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Monday, February 16th, 2015 AT 8:51 AM
Tiny
HMAC300
  • EXPERT
Unless someone has changed the wiring or it may be old as well. it should be brown on one side and pink on other. regardless check for power on both sides if power on one but not the other then the inertia is bad or the switch has popped.or you can use an ohm meter and see if you get 0 through both. Here are the engine and fuel pump wiring diagrams with the guide to help you do some testing.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (Below). Please run this test and get back to us.

Cheers
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Monday, February 16th, 2015 AT 9:32 AM
Tiny
BHERBIN
  • MEMBER
Thanks for the guide I found the problem was a connection at the relay all corroded the truck is running great! Thanks for you help I love this site.
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Monday, February 16th, 2015 AT 10:11 AM
Tiny
HMAC300
  • EXPERT
Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers
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Monday, February 16th, 2015 AT 12:08 PM

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