Had a new fuel pump installed in the Z (94 M6) and when the car is running I get what sounds like an audible hissing noise inside the car (coming from the back of the car). I was told this is normal? The replacement pump is an AC Delco unit.

 

I would probably expect that noise from an aftermarket pump but I'm not sure about a factory pump. I would think a factory pump should be very quiet. Even my 255 lph GMS pump is inaudible.

 

My factory pump is loud at start, usualy thats a good sign its working properly.

Tony.

 

i have a sound too

 

Thanks everybody...

 

it a GM ... 95% of GM have really load fuel pumps ... so you only have a problem if you dont hear that sound ... means its not working