another fuel pump problem
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Junior User
Joined: Jan 2004
Posts: 77
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From: Western MD
another fuel pump problem
hey guys been awhile but i am back. My brothers 2.9 bronco stopped the other day and been trying to help him figure it out. I dont have a diagram but here is what i found. Took the fuse out from passenger side compartment and it is good. Took inertia switch out and not getting any voltage. Back at the pump i am getting 11. something voltage between the two pump wires. However the pump wont run. If i take a hot and ground from the battery back it will come on. Why am i reading almost 12 volts at the pump? Is this phantom voltage? I thought the wiring went from the fuse to the inertia switch to the pump or did i get this wrong? I am going to try to find a diagram but any help is appreciated. By the way where is the fuel pump relay at? Isa it under the power supply strip at the passenger side compartment? Quite possibly this may be the problem. Thanks for any help.
Postmaster
Joined: Oct 2003
Posts: 4,516
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From: SoCal
It's wired from fuel pump relay to inertia switch to fuel pump or pumps.
On my 87 the fuel pump relay is on the passenger side fender.
On my 87 heres how it works. The yellow wire will have 12 volts on it at all times
Red tan/light green & orange/light blue should have voltage only when the key is turned to run.
If you have an 87,check at the fuel pump relay for this voltage.
Other years probably work the same
Edit orange/light blue is wired to the inertia switch & you will only see voltage on this wire for about 2 seconds after you turn the key to run.
On my 87 the fuel pump relay is on the passenger side fender.
On my 87 heres how it works. The yellow wire will have 12 volts on it at all times
Red tan/light green & orange/light blue should have voltage only when the key is turned to run.
If you have an 87,check at the fuel pump relay for this voltage.
Other years probably work the same
Edit orange/light blue is wired to the inertia switch & you will only see voltage on this wire for about 2 seconds after you turn the key to run.
Last edited by 87 XLT; May 14, 2005 at 06:19 PM.
Thread Starter
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Junior User
Joined: Jan 2004
Posts: 77
Likes: 0
From: Western MD
well we put a new relay in and the pump runs...however it runs all the time even with the key off and out of the ignition. Before it did not run and now you cant get it to shut off. LOL. Could this possibly be a bad ignition switch or what?
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