No power to fuel pump

Tiny
TMAN69.69
  • MEMBER
  • 1987 CHEVROLET 1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 80,000 MILES
Me and my grandpa bought this truck and got it running good and had the stock 305 in it. But that blew up so we did a motor swap which is a 350 from the 1970's. But the guy we got it from said it was an 1986. We got the motor in and hooked everything up, some plugs from the air pump and cruise control not there because we didn’t put that back on. We changed the fuel tank because it was leaking. And when we went and tried to start it there wasn’t fuel. You could spray it with ether and it will start. There isn’t power to the relay or the pump but pump works fine we tested it. And the ECMB fuse on the fuse panel blows every time you turn the key on. We can hook a jumper from the tan and white port on the plug that goes in the fuel relay and try to start it then there is fuel coming out of the injectors in squirts like it suppose to. But still doesn’t start which I think is cause it has smaller injectors. Any help would be greatly appreciated.
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Saturday, June 8th, 2019 AT 4:33 PM

6 Replies

Tiny
SCGRANTURISMO
  • EXPERT
Hello,

In the diagrams down below I have included a wiring diagram for you vehicle with the fuel pump circuit in it. I want you to take a voltage reading at the fuel pump of the tan wire with a white stripe. You will need to have an assistant cranking the engine while getting your reading and you will need to use a multi-meter to do this. I have included a link below if you are unfamiliar with how to use a multi-meter.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Please go through this guide, if needed, and get back to us with what the voltage reading was.

Thanks,
Alex
2CarPros
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Sunday, June 9th, 2019 AT 12:07 AM
Tiny
TMAN69.69
  • MEMBER
When I crank the tan wire gets nothing.
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Sunday, June 9th, 2019 AT 10:15 AM
Tiny
TMAN69.69
  • MEMBER
And now the ECNB fuse does not blow when we turn the key on, but the relay is not engaging anymore and still no power to pump.
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Sunday, June 9th, 2019 AT 11:51 AM
Tiny
SCGRANTURISMO
  • EXPERT
Hello again,

Okay, can you test the fuel pump relay for me. It probably has an internal short in it and that is your problem. Anytime you have a fuse that blows, it is caused by a short to ground somewhere in the circuit that it is protecting. I have included a link below for you to go to.

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

Please go through the guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros
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Sunday, June 9th, 2019 AT 12:54 PM
Tiny
TMAN69.69
  • MEMBER
Good news, we found the short and fixed it and now it runs. Thank you for the help Alex. Much appreciated from me and my grandpa.
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Sunday, June 9th, 2019 AT 2:34 PM
Tiny
SCGRANTURISMO
  • EXPERT
Hello again,

Great! That is what we love to hear, that you guys fixed your vehicle. You guys did a great job. Please, if you have any other car questions, feel free to ask. You guys are the reason we are here.

Thanks,
Alex
2CarPros
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Sunday, June 9th, 2019 AT 10:30 PM

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