Fuel pump leaking

Tiny
JENNYANN87
  • MEMBER
  • 1998 CHEVROLET BLAZER
  • 4.3L
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
Fuel pump is pumping out (leaking) gas without the relay even connected. Is that possible? What could be my problem?
Saturday, May 15th, 2021 AT 7:08 AM

2 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Maybe I am not understanding the issue. Where is the leak?

You have the relay removed and the pump is still running? If this is the case, where is the leak and are you sure you have the fuel pump relay removed and not another one?

If this is the case then you have power getting to the pump some other way which means the gray wire highlighted below is shorted to power.

Can you check the circuit and confirm this is the case?

https://www.2carpros.com/articles/how-to-check-wiring

Please see the wiring diagram below. Let us know if we are not understanding and we can go from there. Thanks
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Sunday, May 16th, 2021 AT 7:35 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

If you are pumping fuel with the fuel pump relay removed, you have a short to power which is providing power to the pump at all times.

Looking at the schematics, I noticed the ECMB fuse in the underhood fuse box (right next to the fuel pump relay) is what powers the pump. Do me a favor. Remove the fuse and see if the problem still exists. If it does, we have a short at a different place. If it stops, there is a good chance the fuse box is shorting between the two components.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Below, I attached the wiring schematic for the entire powertrain control system in the event you need them. If you look at pics 5 and 6, I highlighted the wiring to the pump from the relay. Also, I circled the fuse and put an arrow where I think the short exists.

The last pic shows the underhood fuse box. I highlighted the ECM B fuse. That is the one I need you to remove to see if the pump stops.

Let me know what you find or if you have other questions.

Take care,

Joe
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Sunday, May 16th, 2021 AT 8:03 PM

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