My dads fuel pump is making some weird high pitch noise when the car is running. You can hear it louder than the exhaust from the rear of the car. It almost sounds like the sound of a bad leak in a tire.

My first thought was the tank was over pressurized, but I took the gas cap off and there's no hiss at all, so that can't be it. His stock evap line is not capped off, it just vents into the atmosphere under the car. I can't think of what it could be. The car runs without a hitch, no hiccups like it's starving for fuel or anything like that. I'd like to know what it is pretty quickly in case it's something g that requires pulling the tank because we will be playing musical rear ends here soon.

 

thats weird.. mine did too for a day.. it drove me crazy. the next day it acted fine and couldnt hear it. everytime i turn the IGN on i wait for the pump to turn on and stop then i crank. mine made that noise when i just cranked it right away.. also this was my second walbro pump. the first one was deffective and lasted me 2 weeks.. it did give me a loud whine and could hear it pretty damn loud. the noise was coming in and out, but it was still loud even while i was driving! kept spuddering and hesitating, i have a ls1 and had a pressure gauge in my lines and gave me 22psi. then in the end i replaced it and no problems now. give it some time it might just go through a phase i hope.

 

I took it out tonight to a few hang outs and didn't hear it this time... Weird.

 

I had that happen to me with my walbro 255 in the LS car. Same thing, It did it once and never again. Made me distrust it for a few months....

 

I never had it happen in the vert though, but the exhaust is so gosh darn loud you wouldn't be able to hear the pump anyways, so maybe it did it but I just never heard it.

 

My pump on the V6 with stock thirdgen tank wines a little bit once it gets below 1/4 tank. Not full tank of gas?
Replace the fuel filter?
Check fuel pressure?
There is the white valve thing in the back by the tank but supposidly its a valve that only lets air in.
There is also a vacuum controlled valve in the engine bay that goes to the charcoal canister that let's pressure out. The valve can be bypassed and go directly to the charcoal canister.
Just because it's a Walbro doesn't mean it's bulletproof. Anything mechanical/electrical can fail no matter how good the brand is.

 

Actually, I think that valve mounted over the axle is supposed to let pressure out, so the tank/seal/lines dont burst. I have yet to find a replacement for it as GM stopped making it.

 

It's a brand new filter, that white valve thing is still in place, has a full tank of gas, and there is no charcoal canister/evap crap anymore. We took all of that out when we did the engine swap.

I'm pretty sure you can get a generic one from AutoZone.

 

You Mo. guys are lucky! Remove that stuff in AZ and they put you in front of a firing squad! LOL, been looking for one of those check valves for quite some time and havent found anything that will work.

 

GM still sells 4th gen version(s). The 93-97 one is part number 10245442.

 

Possible the "Hissing" is the excess fuel bypassing the regulator? Is it a ls swap? Corvette filter/regulator? Maybe a leak in tank? Maybe do a fuel pressure static test and see if its holding psi?

 

Try living in CA

 

I can barely hear my Walbro 255, even when the engine is off.

I keep getting the function of that white valve confused in my head. But, last time I checked its function first hand, thinking it was a pressure relief valve, I discovered it actually lets air into the tank (prevents vacuum building up in the tank).

 

I have not heard my pump at all and I've only had 5 gallons in the tank since I first started it. Now the stupid heat shields are a different story....

 

Mine will start whining after about 20 mins of driving. And will start loosing pressure and not wanna run. It was the one from hawks.. So its been sitting in the garage for awhile, ill drive it for about 10 to 15 mins and put it back in the garage... Been lazy and havent wanted to replace it again...