Whine

[Shane77624]

I have been blessed with the old '99 GMC NBS fuel pump whine. It used to be able to be fixed by adding some Marvel Mystery Oil to the gas, but it doesn't seem to be working now. I have noticed that the pitch of the whine changes with added or reduced electrical demand (raising or lowering windows). Is there anything I can do to reduce the whine short of changing the fuel pump? I am going to try and change the filter this weekend to see if that helps. Any other suggestions are appreciated.

[sub5]

They all make noise, but when they get louder it's either because of fuel restriction due dirty fuel filter or it's going to quit on you. You probably have the one that has the fuel sending unit included in the assembly and they are not cheap. Also they are very noisy when the tank is nearly empty and they work harder. How many miles on your truck?

[chevroletmb]

these in tank fuel pumps use the fuel to cool the pump so

in theory if u keep the pump submerged it should last longer

and help muffle the noise

[sub5]

Yes that's true, but GM's pump's have other issues such as wiring being too small for the current passing through and the distance from front to rear. I've seen pumps come out of the tank half melted with some of the plastic deformed. My pump was cooked at 100k miles last winter. This new one has 10k miles and it's somewhat noisy. The fuel filter has to be replaced regularly to avoid flow restrictions. if the filter gets real dirty, the pump forces and can burn out. Cost me $750 last year to get it done because I had no time, no garage and it was -30 outside. It stoped working one morning when I had loaded my truck with cabinets to deliver. Fun, real fun.

[Metz Motorsports]

I had the whine when I first purchased my truck (used), and its since went away...is this the calm before the storm?

[sub5]

Can't ever tell, they all react different. Was told they where bad when they made lots of noise. New one makes almost as much noise as the old one, but me too my pump has been more quiet lately. My 40g tank hasn't been below half though. But they do just quit suddenly and same thing has happened to 5 other guys I know here in town. Some have much older chevy PU's with a simple $75 pump, and others like me have the pump and fuel sending in one piece at $500.