99 Ranger fuel pump problem
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Freshman User
Joined: Apr 2004
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99 Ranger fuel pump problem
I have got a problem with my 99 ford ranger it died on me the other day and i found the fuel pump relay fuse in the power distribution box had blown i replaced it and the truck started right back up then died again the fuse blew again and again and again.Finally after letting a sit a day i replaced the fuse again and it started iam stumped.Is this maybe a condition of a fuel pump going out, bad fuel pump relay, kinda weird it has a fuel pump relay and a fuel pump relay fuse, or maybe a short somewhere? dont understand why it will sometimes run and not blow the fuse?
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Post Fiend
Joined: Dec 2001
Posts: 10,562
Likes: 4
From: South Jersey
Fuse 9 really doesn't protect the relay, it's the power source for the pump. I would suspect the pump was unhappy since it's not giving you trouble now. If it acts up again check the circuit for a short to ground.
Senior User
Joined: Jul 2003
Posts: 126
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You'll have to have a tool. I use a multimeter. See what touching the read and black terminals will do when you touch them together on various resistance values (ohm settings).
You'll check the ends of your wires for your fuel pump to see if they do the same thing. Of course, if it is the ground wire that your measuring it should already be grounded. Disconnect the negative battery cable on your vehicle before measuring for any resistance values on your wires. Put one terminal on the wire connector you are testing and one on a known ground (body/frame usually works good). Notice the resistance value on the meter and so on .....
If you get a multimeter, sometimes they have instructions on how to use them. Haynes manuals usually do as well. Have you searched this board?
Good Luck
You'll check the ends of your wires for your fuel pump to see if they do the same thing. Of course, if it is the ground wire that your measuring it should already be grounded. Disconnect the negative battery cable on your vehicle before measuring for any resistance values on your wires. Put one terminal on the wire connector you are testing and one on a known ground (body/frame usually works good). Notice the resistance value on the meter and so on .....
If you get a multimeter, sometimes they have instructions on how to use them. Haynes manuals usually do as well. Have you searched this board?
Good Luck
New User
Joined: Apr 2004
Posts: 21
Likes: 0
Get a repair manual and look at the wiring diagram for your fuel pump system. Get your codes to understand which side of relay is grounding out.
Pull your connectors and run resistance tests on each strech of wiring harness as per your wiring schematic. Wiggle the section of wiring harness you're checking as you go.
Pinpointing a ground isn't easy though. Look for darkened insulation. Where insulation is exposed to heat, double-check it. If it's discolored and stiff, it will crack. Easiest way to check is take a dirty thumb and rub along the wire, the dirt will catch in the crack and make it more obvious.
Also double-check around where the wiring harness hits sharp edges. Vibration breaks occur a lot, so this is your first stop when approaching pinpointing a short to ground.
Pull your connectors and run resistance tests on each strech of wiring harness as per your wiring schematic. Wiggle the section of wiring harness you're checking as you go.
Pinpointing a ground isn't easy though. Look for darkened insulation. Where insulation is exposed to heat, double-check it. If it's discolored and stiff, it will crack. Easiest way to check is take a dirty thumb and rub along the wire, the dirt will catch in the crack and make it more obvious.
Also double-check around where the wiring harness hits sharp edges. Vibration breaks occur a lot, so this is your first stop when approaching pinpointing a short to ground.
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