Fuel pump relay location and wiring diagrams please?

Tiny
CAT DOC
  • MEMBER
  • 2003 CHEVROLET S-10
I have a s10 that the fuel pump wont pump. Put in a new fuel pump and it pump for a few secs and quit. All wires test good and no shorts. Bad relay?
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Friday, September 17th, 2010 AT 9:00 PM

62 Replies

Tiny
MADMIKE1735
  • EXPERT
It does sounds like the relay is bad but to be sure here is a guide to help you step by step with instructions in the diagrams below to show you how on your car.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.
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Friday, September 17th, 2010 AT 9:03 PM
Tiny
CAT DOC
  • MEMBER
Yes I put in a jumper at the relay and the fuel pump will run. I put in a new relay and it fixed it thank you for the guide.
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Friday, September 17th, 2010 AT 9:07 PM
Tiny
JOHN & RAY
  • MEMBER
  • 2002 CHEVROLET S-10
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
Fuel pump not working. Have replaced it with a new one, no luck. No voltage at grey wire to pump.

Have swapped out the relay, no luck

Have check the fuse next to the relay, okay. There is voltage at the fuse (test light)

I have read there is a place where you can test the circuit by providing a 12 volts jumper which should then cause the pump to run (or tell you there is a problem like a broken line - grey wire). But I don't know where this is.

Assuming the line is okay to the pump, what am I missing that is keeping the pump from getting power?

The engine has spark and so on. Does not run. No code comes up via the scanner.
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Saturday, March 6th, 2021 AT 11:35 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Good morning,

Attached a wire diagram for you to view. Please verify powers to the relay with the key on for me and let me know the voltage.

The primer wire you are talking about was for the older models and is not in your truck.

Roy
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Saturday, March 6th, 2021 AT 11:35 AM (Merged)
Tiny
JOHN & RAY
  • MEMBER
So voltage at the ECM B fuse with the fuse removed and the relay in place?
Or fuse in place and relay removed?

(Or both, since I'll be right there?)
Thanks!
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Saturday, March 6th, 2021 AT 11:35 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Fuse in place. Test for power to pin 30.

The other, 86, should only have voltage with the key on for 2 seconds as it comes from the pcm. It will keep voltage while cranking.

If you jump 30 and 87, the pump should run.

Roy
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Saturday, March 6th, 2021 AT 11:36 AM (Merged)
Tiny
JOHN & RAY
  • MEMBER
This makes sense.
My only confusion is on the identification of the 4 pins. If I unplug the relay, I believe the pins are in a rectangular set-up whereas the drawing you provided has them in a linear set up.

I do recall finding voltage at one of them with the key on.

So looking down at where the relay was removed, from the driver's side fender, who is who?

Thank you!
John
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Saturday, March 6th, 2021 AT 11:36 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Look at the bottom of the relay. They should be marked 30, 87, 86, 85.

You jump the 12-volt power or pin 30 to 87 which is the gray wire to the pump.

Roy
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Saturday, March 6th, 2021 AT 11:36 AM (Merged)
Tiny
JOHN & RAY
  • MEMBER
Ah! That takes care of that. Thanks again. Sorry for the ignorance.
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Saturday, March 6th, 2021 AT 11:36 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
No worries. That is why we are here.

Always glad to help.

Roy
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Saturday, March 6th, 2021 AT 11:36 AM (Merged)
Tiny
JOHN & RAY
  • MEMBER
Okay! We got it running. The grounds for the computer and other electrical's were rusted and not working. 218,000 miles in New England does that, sadly.

Thanks for the great information. We have printed it all up and tucked it away for future reference.

John
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Saturday, March 6th, 2021 AT 11:36 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Always glad to help.

Roy
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Saturday, March 6th, 2021 AT 11:36 AM (Merged)
Tiny
WM V
  • MEMBER
  • 2001 CHEVROLET S-10
Fuel pump just stopped took it out of the tank check the connections an no power, checked the relay & fuses all good, have power at the relay, tryed another relay an still no power at the pump, what am I missing?
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Saturday, March 6th, 2021 AT 11:38 AM (Merged)
Tiny
2CEXPT
  • MEMBER
The computer energizes the fuel pump relay and relay will de-energized in 2secs. At which time when the vehicle fires up the oil pressure sending unit powers the pump-All you got is 2secs to check for power at the connector. Also see below


https://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_48.gif

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Saturday, March 6th, 2021 AT 11:38 AM (Merged)
Tiny
MWEBBERTN
  • MEMBER
  • 2001 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 153,009 MILES
Engine turns over but will not start. Did not hear fuel pump running when ignition is only in on position. Checked fuses and fuel pump relay. Can hear the fuel pump relay click when the ECM B fuse is inserted with the ignition in the on position. Replaced fuel pump. Still behaves the same way.
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Saturday, March 6th, 2021 AT 11:39 AM (Merged)
Tiny
MWEBBERTN
  • MEMBER
I completely forgot to go in here and update this post after I fixed the problem. I was going through some old e-mail and saw where I had signed up for this forum and realized that I never updated it. So here goes. Over a year later. However, the problem was fixed in a few days! I had taken the bed off of the truck to make it easier to change the fuel pump. After replacing the fuel pump I tried to start the truck. No luck, same as before. Getting to the point of giving up. I went ahead and put the truck bed back on again. I just happened to be sitting in the drivers seat just wondering what in the world could be wrong when I reached down and for some reason just turned the key. It started! The only thing I can figure is that there was a ground wire that needed to be connected that wasn't when the bed had been off. But anyway, the new fuel pump did fix the problem and the truck has run great this past year.
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Saturday, March 6th, 2021 AT 11:39 AM (Merged)
Tiny
REGIS STROHMEYER
  • MEMBER
  • 2000 CHEVROLET S-10
After a large snow fall, my pickup wold not start, it would turn over but it would not start. My fuel pump seemed not to start. It normally makes a winding sound when I first turn the key on. I checked the fuses(2 of them) I checked the relay and swapped out the horn relay. They both work. I then purchased a new fuel pump, but had to replace the harness because the new pump had a different connector. It came with a harness.
I plugged in the new pump but still dosen't sound like it is running. I tested the old pump the same way before I changed the harness. How can I check the pump electronicly and what else can I check before I install the tank.
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Saturday, March 6th, 2021 AT 11:40 AM (Merged)
Tiny
JDL
  • EXPERT
Hi, First, I would have used a gage and checked fuel pressure, engine cranking, before changing anything.

Take the fuel pump connector loose, then, engine cranking, check voltage and ground at the pump connector. Gray wire is voltage for pump motor, black wire is ground. Not sure how safe to try to run pump with oxygen in the tank?? If no voltage on gray wire, check wiring circuits at the relay.


https://www.2carpros.com/forum/automotive_pictures/170934_s10_fuel_pump_relay_3.jpg

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Saturday, March 6th, 2021 AT 11:40 AM (Merged)
Tiny
PURLJM
  • MEMBER
  • 1999 CHEVROLET S-10
  • 4 CYL
  • 2WD
  • MANUAL
  • 13,300 MILES
Where is the fuel pump relay? Engine is not getting fuel somehow and I am troubleshooting. Plenty of battery just won't turn over. Thank you
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Saturday, March 6th, 2021 AT 11:40 AM (Merged)
Tiny
JDL
  • EXPERT
Hi, the relay is located in underhood fuse box. Here is guide to help check it with the relay location below.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (Below). Please run this test and get back to us.
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Saturday, March 6th, 2021 AT 11:40 AM (Merged)

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