Fuel pump ground
The relay is triggered by the computer with a ground signal. That wire is blue/orange and with the key on and that wire grounded the fuel pump should come on. It's at the fuel pump relay but also goes to the diagnostic connector, that's the best spot to attach the ground to test the pump. I haven't had the truck tank(s) out yet, but the ground usually comes off the assembly and bolts to the frame.
Senior Member
Joined: Jul 2008
Posts: 58,557
Likes: 1,165
From: Long Beach Calimexifornia
The relay is triggered by the computer with a ground signal. That wire is blue/orange and with the key on and that wire grounded the fuel pump should come on. It's at the fuel pump relay but also goes to the diagnostic connector, that's the best spot to attach the ground to test the pump. I haven't had the truck tank(s) out yet, but the ground usually comes off the assembly and bolts to the frame.
Junior Member
Joined: Mar 2023
Posts: 2
Likes: 0
From: PNW
Did you ever find the ground? Think dealing with the same problem on my 90. I probed the wire that goes to inertia switch and eventually to pumps to see if had power, and the pumps would come one when I ground the test like, kick off it I took off test light ground
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
This thread is more than a decade old, and your post is almost unintelligible. Take a few extra seconds to proofread & edit it; or just start a new thread with a better description of the symptom. You should also put ALL your truck's details & history (as much as you know) into your signature so it shows with each post, as this page explains:
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Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Put your location (nearest city) in your profile &/or signature, & upload an avatar of the truck. The more pics you post (NOT in your sig) of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now.
(click this text)
Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Put your location (nearest city) in your profile &/or signature, & upload an avatar of the truck. The more pics you post (NOT in your sig) of the truck, engine, wiring, labels, & undercarriage, the more likely we can help you. Not all its details are relevant to these issues, but you don't necessarily know which ones are relevant, so just put everything in now.