Hi,

I have a 96 4,3 4door 4x4 blazer.
Today i heard a buzzing noise near rear wheels.
I think it is the fuel pump. But why it is running when ignition is off.

 

How long did you hear it run for? Have you confirmed that it is the fuel pump? If you remove the fuel pump relay does the noise stop?

 

It was only a gess that is if fuel pump. buzzng was coming from rght side of a car. and i was unable to locate fuel pump relay :S. I found relay box from a clove box but removing thed did'nt stop the buzzing.

 

fuel pump relay i beleive is under the hood. not 100percent sure .. does the sound go away when you stop or does it make the noise when your moving...?

 

I dont know about moving but whan i stop the engine and take off the key it keeps buzzing.
Yesturday morning i had to take the bus to work because my battary was dead:S
I looked under the hood but i didn't see any box that looked like fuse box.

 

Yesturday eavning I unpluged the battary because it was still buzzing.
Today I put battary back on and everything was quiet. I drove to work, turned off the engine and buzzing was gone. I hope it will not come back.

 

Weird. Maybe a relay stuck closed and the battery disconnect allowed it to open...

 

yep. I thin it is the relay. Sometimes when i stop the engine it will keep buzzing and sometimes not. When it is buzzing and i unplug the pattary for a few seconds and plug it back it will keep buzzing. Probably it is just worn out.