fuel pump problems
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Cross-Country
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From: London
fuel pump problems
I have a 91 F-150 straight 6 cylinder supposed to have dual tanks but front has been removed. Thought fuel pump was out, replaced it. still wouldnt kick on. Replaced fuel pump relay, still nothing. BUt i used a test light and grounded a wire coming off the relay and the fuel pump kicked on but wouldnt kick off untill i released the test light from the wire. Got a clue?
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From: Easton,Ks
Originally Posted by blueovalfan
I have a 91 F-150 straight 6 cylinder supposed to have dual tanks but front has been removed. Thought fuel pump was out, replaced it. still wouldnt kick on. Replaced fuel pump relay, still nothing. BUt i used a test light and grounded a wire coming off the relay and the fuel pump kicked on but wouldnt kick off untill i released the test light from the wire. Got a clue?
The computer grounds the coil of the fuel pump relay for one second when you turn on the key and it will ground it again when it sees a PIP train from the distributor. It will then remove the ground again one second after the PIP train stops or when you turn the key off.
Last edited by subford; Nov 6, 2007 at 06:54 PM.
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From: Easton,Ks
Originally Posted by ReadOrDie_DW
Ok so he has the wrong relay then right? The fuel system isn't something I've had much trouble with yet (thank goodness)
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From: London
I checked the inertia switch the button is not up. When i turn the key on the pump does not kick on , when i use my test light and ground one of the wires in the relay it makes the pump kick on . When I remove it the pump shuts off
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From: Easton,Ks
Originally Posted by blueovalfan
I checked the inertia switch the button is not up. When i turn the key on the pump does not kick on , when i use my test light and ground one of the wires in the relay it makes the pump kick on . When I remove it the pump shuts off
By the way there is nothing wrong with your inertia switch or fuel pumps.
If they do not come on for the one second then you have a either a wire problem to the computer from the fuel pump relay coil or a bad computer.
Try grounding pin #6 of the DLC (test connector/VIP connector), turn on the key and see if the pumps run as long as the pin is grounded.
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From: Easton,Ks
Originally Posted by blueovalfan
The pump does not come on by just turning the key on. When i grounded the #6 pin the pump did kick as long as the pin was grounded .
But first check and make sure that the small black wire with a white (maybe green) strip near the batteries NEG post or at the end of the small black wire leaving the NEG post and screwed to the body is well grounded. This is the only ground for the computer and it must have this ground to run the engine.
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PCM location
Originally Posted by blueovalfan
The ground seems to be ok , where is the computer? Is it easy to change? I have never messed with the computer on any truck
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From: Easton,Ks
Originally Posted by HMR-RSQ
Heh dude having similar problems. The computer is located behind your left kicker panel. The bolt and connector is under the hood at the firewall
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