no power to fuel pump

[mcook4]

Changed spark plugs after truck was starting to hesitate at times and shortly after that it wouldn't even start. Checked with tester and found no power getting to fuel pump and can't seem to find the problem. Any suggestions?

[robertjr]

what year is your truck?

[mcook4]

1997

[robertjr]

most likely its relay or fuse but there could be larger problems as well so I would start there

[sherman69]

The fuel pump only gets power for 3-5 seconds when you first turn on the key, just to pressurize the injectors. Then after it starts it gets power through the relay that gets energized.
If it cranks long enough to get the oil pressure up to around 5 lbs, it will get power through the oil pressure switch.
For troubleshooting, there is a short pigtail below the power brake unit, just behind the fuse box. If you put a jumper on it from 12 volts the pump should run continously.
There might be two pigtails there. I believe itis red.
Also you can get 12v right there if you pop the cover off the fuse box, the big red wires on the rear are hot 12v. The relay for the fuel pump is in that fuse box with a diagram in the cover identifying it.
Bob B

[mcook4]

We checked the fuses and those were fine. What do you mean by pigtail and jumper? I think by pigtail you mean an extra part coming off the main line, but am not sure.

[sherman69]

Originally Posted by mcook4

We checked the fuses and those were fine. What do you mean by pigtail and jumper? I think by pigtail you mean an extra part coming off the main line, but am not sure.

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The pigtail I mentioned is a short piece of wire with a plastic connector on it but not pugged to anything.
By jumper, I meant a piece of wire to feed from a 12 volt source to the pigtail.
Yes the pigtail comes out of the main harness and sticks out a few inches.
I found mine behind the big relay/fusebox on top of the left fender and just under the power brake unit.

Good luck,
Bob B

[mcook4]

Thanks for all your help. We finally decided to take the truck into the dealership and found the problem was the ignition switch. Thanks anyway!