Fuel pump wiring and relay location?

Tiny
STEVEN TUCKER
  • MEMBER
  • 2007 CHEVROLET EXPRESS
Van is not getting any fuel. Have checked all fuses. Trying to narrow down the problem to determine if it is the fuel pump but not sure if any sensors, wiring or relay could be the problem.
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Saturday, December 5th, 2009 AT 12:57 PM

19 Replies

Tiny
RASMATAZ
  • CERTIFIED MECHANIC
Do you hear the fuel pump come on for a few secs if so check the fuel pressure if not recheck the fuel pump fuse and fuel pump relay here is a guide to help with the fuel pump relay test and location below and engine wiring diagrams.

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

Check out the diagrams (Below). Please let us know what happens.
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Wednesday, November 7th, 2018 AT 5:46 PM
Tiny
STEVEN TUCKER
  • MEMBER
I do not hear the fuel pump. I have checked the pressure and have none. Fuses and FP relay are good.
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Wednesday, November 7th, 2018 AT 5:46 PM
Tiny
RASMATAZ
  • CERTIFIED MECHANIC
Check for power at the fuel pump connector and the ground side of the circuit
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Wednesday, November 7th, 2018 AT 5:46 PM
Tiny
STEVEN TUCKER
  • MEMBER
Should there be constant power there or just pulses and if power is there I would assume its the fuel pump so I got a new one everything is working again, thank you
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Wednesday, November 7th, 2018 AT 5:46 PM
Tiny
RASMATAZ
  • CERTIFIED MECHANIC
Nice work, we are here to help, please use 2CarPros anytime.
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Wednesday, November 7th, 2018 AT 5:46 PM
Tiny
BRUCEJ455
  • MEMBER
  • 2004 CHEVROLET EXPRESS
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 320,000 MILES
Cannot get new fuel pump to run. Relay will not energize and gray wire has no bat on it. If power is put to gray wire back at frame rail near pump it will run and engine will start. Had no ground to terminal 35 of relay. Replaced PCM and got ground. Still have no bat to terminal 35. Have jumper-ed term 30 to 76 (wire that is supposed to run to fuel pump and pump is not energized). Checked ignition 1 and ignition 2 fuses and are okay. Read could be oil sw so replaced. Still will not energize fuel relay. Am stumped.
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Monday, November 16th, 2020 AT 5:18 PM (Merged)
Tiny
ASEMASTER6371
  • CERTIFIED MECHANIC
Good evening.

On the relay, 30 is powered by a fuse from the fuse block. It is shown in the diagram I sent. 30 is for the load side.

The control side ground comes from the PCM. When the key is turned on, it will power pin 85. Then after two seconds, it will shut off. It will send constant voltage cranking and running.

Here are the engine and fuel pump wiring diagrams so you can see how the system works.

Check out the diagrams (Below). Please let us know what happens.
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Monday, November 16th, 2020 AT 5:18 PM (Merged)
Tiny
BRUCEJ455
  • MEMBER
Roy the PCM is new so what you are telling me is PCM supplies both the ground and power to relay. If that is the case then I need to return PCM and get a refund or one that is good. Correct?
Bruce
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Monday, November 16th, 2020 AT 5:18 PM (Merged)
Tiny
ASEMASTER6371
  • CERTIFIED MECHANIC
If you look at the diagram, yes, the PCM controls the control side of the relay.

That is why you need to verify that voltage. If there is no voltage, then yes, the PCM is the issue.

Roy
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Monday, November 16th, 2020 AT 5:18 PM (Merged)
Tiny
MDM6713
  • MEMBER
  • 1997 CHEVROLET EXPRESS
Electrical problem V8 Two Wheel Drive Automatic 155000 miles

1997 Chevy Express 2500 Van 155,000miles, Engine died in parking lot, we installed a new fuel pump, but noticed no power to Grey wire going to pump. Check the relay and it bench tests fine, however, no power is sensed at the proper terminal to turn on the relay. Not even a 2 second pulse when cycling the key of and on. Whats the next step I should take?
Thanks a lot
Michael
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
RASMATAZ
  • CERTIFIED MECHANIC
Hi mdm6713 and welcome to 2carpros

It sounds like you have a power failure such as a bad connection or a trigger failure of such kind, here is the fuel pump wiring which is in the engine wiring (below) so I gave you the entire engine wiring diagram and a guide so you can do some testing.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-wiring

Please run this test and get back to us so we can keep helping you.

Cheers
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
MDM6713
  • MEMBER
Actually I was wrong, I did have the 2 secs worth of power at the relay. This is what Im expeirencing now, The fuel pump will cut on for the 2 secs time only if the oil pressure switch at the rear of the engine is disconnected. Does it sound faulty? Another thing, I can jump the wires on the oi pressure switch and the pump will operate. However, it will only blow air, no fuel. I re-assemblied this twice already. Can you think of what Im doing wrong? Thanks a lot for your help
Michael
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
RASMATAZ
  • CERTIFIED MECHANIC
If the fuel pump comes On for 2 secs it should produce pressure -check it with a fuel pressure gauge and report back your readings. When the engine fires up this is where the oil pressure sending unit powers the fuel pump.Also check for injection pulse width with a noid light

Your OPSU is okay if it turns On the pump while jumpered and key at run


https://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_80.gif

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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
MDM6713
  • MEMBER
Ok, I bench tested the pump to make sure I wasn't crazy, pumped fine. What I did was fill up the capsule with fuel while inserting into the tank, (primed it in a way) Well, started right up. I dont know if thats a common problem but I was surprised not to find anything online about priming the pump.
Michael
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
Its sounds more like you had a bad connection at the pump which is a common failure.

Here is an AC Delco pump for 157.00 on Amazon

https://www.amazon.com/gp/product/B00171UG4G/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&tag=2carprcom-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B00171UG4G&linkId=ab2a6bb147556d7f0b2a6c2651f00e52

Please let us know what happens.

Cheers, Ken
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
GBECKER
  • MEMBER
  • 1997 CHEVROLET EXPRESS
  • 150,000 MILES
Key on, no pump. No 2 sec run. No power to pump. All connections good and clean. Replaced pump after no operation w/ power. Found and repaired loose connection after replacement failed twice since. Seems to only happen when warm, parked for 45-hour. Tearing hair out soon.
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
FIXITMR
  • CERTIFIED MECHANIC
Under hood in relay box here is a guide to help you and the relay location in the diagrams below.

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

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
GBECKER
  • MEMBER
It's jammed under the top of the drivers side fender. Where someone with large hands (like me) wouldn't even look for it.
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Monday, November 16th, 2020 AT 5:19 PM (Merged)
Tiny
FIXITMR
  • CERTIFIED MECHANIC
Do you have a picture you could contribute? Our manuals show it in the under hood power center. Unless the van is maybe a late 96 it may be different
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Monday, November 16th, 2020 AT 5:19 PM (Merged)

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