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Fuel pump not working, fuse or relay?

Tiny
CHUNKY
  • MEMBER
  • 4 POSTS
  • 1990 CHEVROLET SILVERADO
1990 Chevy Silverado V8 Two Wheel Drive Automatic

the truck has new fuel pump but I have no power the pumps not coming on and I lost power to my signals could it be a relay because iam not getting power to the pump fuse.(Please help)
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
If you have a fuel module, the voltage to the fuse may come from the fuel module. My info showed for 5.7 hd only and then said L05 and L19, which I guess is a manufacturer ID designation.

The only location I found for the module, where applicable, is next to the pcm. The wiring colors, brown is ignition feed, Black with white tracer is ground for the module, Tan with white tracer is voltage for the fuse. I don't like trying to follow those spaghetti diagrams, sometimes I lose my circuit. LOL
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
CHUNKY
  • MEMBER
  • 4 POSTS
Could you tell me where the fuel module on this truck is located c1500
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
It should be located by or next to the computer. Under the dash, passenger side, behind glove-box cavity.

I gave you the wiring colors for the connector. I'd check the circuits. You didn't list the liter size of your engine?
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
CHUNKY
  • MEMBER
  • 4 POSTS
Thanks for your help its a 5.7 and I checked all the fuses I could find and there all good I noticed if I disconect the fuel relay and bypass the plug it all works but the truck won't turn off with key
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
CHUNKY
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Maybe the ecm and if where is it located
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
ANDREWS72400
  • MEMBER
  • 2 POSTS
  • 1990 CHEVROLET SILVERADO
  • 156 MILES
I have a 90 chevy truck with a built 400 sbc 454 tbi and 350 injectors. I just build it and put it in and to feed the 400 I put a external fuel pressure regulator and a 255lph 100 psi fuel pump. I have it set at about 20 psi and it wont go above that with this fuel pump. With this fuel pump I had to change wiring plug to fuel pump, do you think I may have put wires back wards? The 400 wants more fuel need more pressure.
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I've already told you where the ecm and fuel module should be located, behind the glove box cavity on the passenger side. You need to test the circuits for the fuel module.
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Monday, July 6th, 2020 AT 4:41 PM (Merged)
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
You are using the throttle body injection correct? The regulator in the throttle body will not let the fuel pressure get higher because it is made to run on 15 psi. If you are trying to maintain the computer then you need to get in touch with Jet Electronics and get the computer redone to accept what you have done. I have done this before for a customer with a 383 stroker and it was a learning curve. The older computers do not like the bigger cams makes them over fuel and then the O2 sensor kicks in and leans it and so forth.
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Monday, July 6th, 2020 AT 4:41 PM (Merged)

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