Fuel pump relay location

Tiny
BMH43040
  • MEMBER
  • 1990 CHEVROLET TRUCK
  • 6 CYL
  • 2WD
  • MANUAL
  • 150,000 MILES
A"new fuel pump" was supposedly put in a few months ago. Truck died and not getting any gas to the throttle body. Checked the fuel pump fuse under the hood and it was good but when I checked to see if it was recieving any current it wasn't.I jumped the fuse from the battery but still no gas.I cannot hear the relay kicking in either. Question is does power go to the fuse first or the relay first?The relay does have power going in but I can't seem to find the power going out. Also where does the power come from to the fuse?
Wednesday, April 2nd, 2008 AT 2:55 PM

10 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Power to the fuse comes from the relay and while engine is running with the correct oil pressure it comes from the oil pressure switch. Here is a wiring diagram and the relay test guide and location below.

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


https://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_41.gif



Check out the diagrams (Below). Please let us know what happens.
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Wednesday, April 2nd, 2008 AT 3:08 PM
Tiny
PHILMOSS
  • MEMBER
  • 1 POST
  • 1990 CHEVROLET TRUCK
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 225,000 MILES
I got this old truck, cheap, as the tranny was bad and the owner knew it, and, it had been sittin' for two years. I've tinkered with it some before I pulled the tranny, and took it to a rebuild shop I know. After some intricate troubleshooting, I hadda replace the Ignition Electrical Switch, NOT the KEY switch. You know, the one on top of the steering column, below the dash? OK, a little tough, but do-able. THEN, when trying to start the truck, just to see if the tranny would move it at all, I wasn't getting any fuel at the TBI. With a prime, from a jug of gas, it would "bump-start" and idle for several seconds, without pedal manipulation. Listening, I could her nothing from the fuel pump with the key on. I've changed a fuel pump before, on my 93 Chvy 4wd P/U. Not too tough, at all. So, just recently, when I yanked the tranny out of this 90 model 2wd, I went ahead and changed the fuel pump in the tank. When done puttin the tranny back in, it wouldn't start without a prime. Listening, NO SOUND from the pump! OK, OhmMeter in hand, with the key on, I found NO voltage at neither ther FUEL PUMP RELAY, nor the FUEL PUMP RELAY FUSE that was right beside it on the firewall. OK, I jumped 12v to that fuse right from the batt to check the system, and I heard the pump start running. Still, won't start without a prime, and then dies. I loosened the line at the back of the TBI, and powered up the fuel pump. Gas ran out around the fitting almost instantly. Tightened it up and the pump never shut off. Then, it still needed priming. I can see that the injectors aren't shooting anything! OK, are the injectors and the fuel pump relay fuse on the same circuit? I appear to have a loss of voltage on both, and only these two items on the pickup. All the fuses seem to be good with an Ohmmeter. Didn't see one for fuel pump, but saw the INJ fuse, and it was good, 12v showing. How do I troubleshoot the power supply to the fuel pump relay fuse, where does it come from, and the same goes for my injectors, how do I check 'em to see if they work. And, does the "hotwire" I have to the pump, it just replaces one that is for some reason not present, but would that keep the pump from shuttin off when pressured up? It ran the whole time I worked at troubleshooting, never quit, till I unhooked the wire I jumped from the battery. Need help with this one, as I am no Wiring Whiz, lol. Thanks, Phil
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
SLIMWILLIE
  • MEMBER
  • 4 POSTS
You need to ck the fuseable links at the starter. They will be made of a special wire that is the actual fuse. DO NOT use a peice of wire to repair it but if you find one bad (try to stretch each one or test with a test light on the wire side)you can use a peice of wire for TESTING ONLY. It's very common to find one blown. Look for it to be shorted to exh. Manifold. Usually caused when changing starter.
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
JERRYK66
  • MEMBER
  • 2 POSTS
  • 1988 CHEVROLET TRUCK
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
I do not have 12 v going to fuel pump. I changed the fuel pump relay and checked fuse under hood. Where does it go from there
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the inline fuse 20amp
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
JERRYK66
  • MEMBER
  • 2 POSTS
Where is the fuse at?
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
4092KEITH
  • MEMBER
  • 4 POSTS
  • 1989 CHEVROLET TRUCK
  • V8
  • 4WD
  • AUTOMATIC
  • 176,000 MILES
I replaced the fuel pump about 2 years ago with a over the counter deal. I don't drive it much however the other day it broke down, had it towed home, put some gas down the carb, and it started and ran for a few secounds, and stalled. Repeated same, results same. I was thinking maby fuel pump shot. Or fuel pump relay. If relay, how do I check. Any help that you can give me would be really appreceiated. Thanks,

keith
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi:
The relay usually is fine. However, the pump is another problem. Before anything, check the fuel pump pressure after the filter and before it. It could be something as simple as the filter or the pump may have gone again.

Joe
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
CJACKSON
  • MEMBER
  • 1 POST
  • 1989 CHEVROLET TRUCK
I have 1989, Chevy 4X4 Long Wheel Base Truck with a 350 motor. Mileage is 150000. The truck started cutting out and trying to stall about a week ago. We had been having really cold weather and I figured it was just the cold. Three days ago the truck quit cranking. If I pour gas directly into the breather the truck will crank and will run until the gas I poured in is gone. I checked the fuel pump, the fuel pump is engaging and there is plenty of PSI. I have checked the relays, no problems there. I have checked to make sure I am getting power at the injectors, no problem there. I don't have a noid light, so I have not been able to check the pulse at the injectors. I replaced the Fuel Pressure Regulator and I am still not getting gas through the injectors. Is it the injectors, or something else?
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Putting gas in it makes it run till it burns it all-

if its not the injectors-than it must be the PCM-computer. Try check the crank shaft position sensor too. To include the ground circuits to the PCM
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Tuesday, August 27th, 2019 AT 1:10 PM (Merged)

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