No power to fuel pump, pump does work, wiring harness is good?

Tiny
BOCUTTY614
  • MEMBER
  • 2006 BUICK RENDEZVOUS
  • 3.5L
  • V6
  • 4WD
  • AUTOMATIC
  • 169,000 MILES
Conducted a continuity test from pump harness to wires at back of junction box in floor positive side ground side all beep and pump runs strong with power connected from a battery test light fuse 1 under hood good probed relay pin87 has power jumped pin87&30 no power at pump but when do the continuity test from ground side of junction pin the frame it beeps swapped relays and also Replaced with a new one still no power to pump.
Wednesday, February 28th, 2024 AT 6:21 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Pins 87 and 30 are the secondary side of the relay. If you have power at 87 and jump power to pin 30, the pump should have power. If it doesn't, you have an open circuit between the relay and the pump. See pic below.

What do you mean when you say the ground side to the frame has continuity? If you are checking pin 30 to the frame, you could simply have a broken wire that is shorted to ground.

If you run 12v from the battery to connector pin 30, does the pump run?

Let me know.

Joe

See pic below.
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Wednesday, February 28th, 2024 AT 8:27 PM
Tiny
BOCUTTY614
  • MEMBER
  • 2 POSTS
I haven't put power from battery to pin 30 just because I thought that if pin87 has power (verified with test light) and I mean test continuity on the ground side of pump harness pin3a to frame to ensure it has ground and when I check the positive side of harness pin3c for power with test light no power light doesn't light but if I test pin3h at the harness test light lights dim I believe it's just because it's the 5v reference is there somewhere else that power goes after the under hood distro box before it reaches the fuel pump if not could pin30 in the distro box be faulty but I'll try 12v to pin 30 if it doesn't activate pump then the issue would be in the box if it doesn't go somewhere else before the pump or maybe PCM it's giving me a headache.
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Wednesday, February 28th, 2024 AT 8:56 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Try that and let's see what happens. If it doesn't operate the pump, there has to be an open.

Let me know.

Joe
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Thursday, February 29th, 2024 AT 7:35 PM

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