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Plea for help - No power to fuel pump

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Old 09-30-2010, 01:55 AM   #1
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Default Plea for help - No power to fuel pump

Greetings everyone. I own a 1985 ford F150 xlt lariat with dual tanks and I'm having a bit of a problem with it. I installed a new fuel pump but I'm not getting 12V power at the plug. I have checked all the fuses on the the floor fuse block and they all appear okay. Where else do I need to check?
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Old 09-30-2010, 09:00 AM   #2
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Is it EFI or carb?
Check fuel pump relay.

If EFI remember that all 3 fuel pumps will not have power if the engine is not running. When the ignition is first turned to the run position then the fuel pump will run for about 3 seconds then shut off, (by the relay) if the engine does not start.
There is a way to jumper the relay to force it to stay on for testing - otherwise you need to have a person switch the ignition off and on repeatedly.

The carb system only has 1 pump I don't know if power stays on or not?
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Old 09-30-2010, 11:05 AM   #3
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Thanks for the reply. Where do I find the relay and how do I jump it.
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Old 09-30-2010, 11:50 AM   #4
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Ok. The relay is on the driver's side near the fender but in the corner in a box near the cab. You don't jump this, but you will need to check it. Sometimes the connections to the relay become loose, or you may need to replace the relay. Now on the other fender near the starter relay is a hex shaped red plug looking thing. This is the eec self test interface. To test fuel pumps you will need to take a wire and stick it in the far right port if the long side is facing downward and ground it to the chassis somewhere. What I did yesterday (I had this problem too and it took me a few hours to figure out) is leave it grounded and play with the relay until it comes on. My bet is that one of the wires on the relay came loose and you need to push it back in or replace the relay.

Click the image to open in full size.

This is the eec interface near the passenger fender. Look at the bottom right pin. You will need to ground that pin to the frame. Rig it good and let it sit so you can play with the relay to see when you hear the pump start. Remember, the key must be in position 2.

Click the image to open in full size.

Here is the location of the relay. There are 2 in that box. There are 2 phillips head screws holding it in place. It is on the corner of the driver's fender and firewall. When you pull the relays out the one nearest the rear of vehicle is fuel pump. Play with it while the eec is grounded to see if you can get it to work. The wires may be loose to the relay. Push them in and make sure they are secure. If nothing happens, replace the relay.

I need a favor from you. Please take pictures of the relays and where they both go. My truck has another relay in there with no home and I think it may be the horn relay. I need to see where the wiring goes so I can replace it. Thanks. Let me know what happens. I would have to say this is for sure your problem.
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Old 09-30-2010, 11:55 AM   #5
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Also, Shodog, do you have the fuse location diagram? It should be on the fuse box cover. Mine is missing. If you have it maybe you can take a picture and post of send me. Thanks.
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Old 09-30-2010, 12:33 PM   #6
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Thanks so much for the info. I will take pics of the relays. I don't have the cover to the fuse box either. I'm going bust out and buy the Haynes manual and see if it has the fuse diagram
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Old 09-30-2010, 12:52 PM   #7
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It doesn't and does not really cover our efi 1985. I find that the focus is on old carb and newer efi, whereas the old manual I have too focus too much on carb and not really efi. So, our year is that 85-86 efi that gets left out for the most part. It sucks.
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Old 09-30-2010, 04:55 PM   #8
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Hmm that's dissapointing about the lack of EFI info.
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Old 09-30-2010, 07:47 PM   #9
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Quote:
Originally Posted by walter34payton2002 View Post
Also, Shodog, do you have the fuse location diagram? It should be on the fuse box cover. Mine is missing. If you have it maybe you can take a picture and post of send me. Thanks.
Here is a fuse diagram from the '86 F150\ Bronco shop manual:

http://i608.photobucket.com/albums/t...86F150fuse.jpg

Last edited by klricks; 09-30-2010 at 07:49 PM.
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Old 09-30-2010, 08:08 PM   #10
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Quote:
Originally Posted by Shodog View Post
Thanks for the reply. Where do I find the relay and how do I jump it.
Here is the relay location:
http://i608.photobucket.com/albums/t...150FPrelay.jpg

I also forgot about the inertia cutout. It can trip in a collision or even rough 4x4 activity. The inertia cutout is located inside the cab up near the heater vent on the passengers side. Small box with white reset switch on top.
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