Electric fuel pump

Tiny
ROMA SMITH
  • MEMBER
  • 2004 PONTIAC SUNFIRE
  • 90,000 MILES
I own a 2004 Pontiac Sunfire. My issue is crank no start no power to the fuel pump. I started with the fuel pump relay switch. I established the control side of the circuit was good and that the supply power back to pump was good. A new fuel pump was installed pervious to this no start issue. So I wanted to directly check the pump itself. So on the bottom side of the car I disconnected the fuel pump wiring connector from the underside. I wired two jumper wires directly from a good 12volt battery neg and pos posts. I then wired neg to black ground terminal and pos to the gray power terminal on the connector going straight to fuel pump. The fuel pump came on. I tested the power to fuse on inside driver panel, FP/inj, it was good. Now on the under side the I did get a reading for ground integrity, but nothing on power?Under back seat I used a paper clip to check power nothing? Where is the problem
Monday, November 9th, 2020 AT 8:41 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

If you use a jumper wire at the relay between the gray and pink wires, does the pump run? Take a look at the attached pic.

Also, do you get a low voltage signal from the PCM to the dark green and white wire at the relay which is what actuates it to send power to the pump?

Also, confirm continuity to ground at the relay.

Let me know.

Joe
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Tuesday, November 10th, 2020 AT 8:47 PM
Tiny
ROMA SMITH
  • MEMBER
  • 3 POSTS
It was a loose gray/power wire that ran from under backseat along the driver rail up to a connector in dash. Moved it while key was on and it came on. Thank you very much for your help.
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Saturday, November 14th, 2020 AT 8:41 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

You are very welcome. I'm glad to hear you found it.

Please feel free to come back anytime in the future if you have questions or need help. You're always welcome here.

Take care,
Joe
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Saturday, November 14th, 2020 AT 8:50 PM

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