sixspeedfirebir

Whenever my car is running I have a strange high pitched humming sound coming fromt he back of the car.

At first I though it was a speaker grounding out or something to that effect, but I turned off the radio and the sound was still there. Then I tried turning the key to 'acc' or 'on' with the radio on while the car wasn't running and the sound wasn't there.

So then I was thinking exhasut, but when I give the car a little gas the noise doesn't change at all. I figured if I was something with the exhaust the sound would change a little when I touched the gas, but it didn't.

Anyone have any ideas on this little problem? It doesn't seem to have any adverse effects, but its kind of annoying because every now and then I like to turn the radio off and just listen to that beautiful LS1.

Any help would be much appreciated. Thanks everyone.

Fuels94TA

Have you done any gear change or fuild change lately? If so make sure you use limted slip additive.

sixspeedfirebir

I thought about that to, but it does it in neutral when I'm sitting still. Also I just changed the gear oil and additive about 8,000 miles ago. And it sounds like its coming from inside the car.

Thanks though.

anasazi

fuel pump is on its way out

Capn Pete

I was just gonna say...probably the fuel pump. *Cross your fingers* it's not actually going bad...maybe just getting a little noisy??

sixspeedfirebir

crap... I hadn't thought of that at all...

I'm pushing right at 71,000 miles. Does that sound about right for a fuel pump? About what would that cost if I have to fix it? 12 disc changer I'm trying to get might have to wait....

Capn Pete

For cost saving's sake, I'd recommend doing it yourself if you've got the means. The stupid pumps in these cars aren't exactly cheap, and the labour cost is a bunch to have a shop install it too. To do the pump you gotta drop the rear end, muffler, and gas tank...very labour intensive for something so simple. Now you CAN cut a hole from in the trunk directly over top of the fuel sending unit and access it that way...a friend of mine replaced the one in his '95 himself using that method, and he's not even a mechanic...it saves a bunch of time and work. Even if you have someone do the job for you, it would probably be a good idea to suggest they do that instead of the "proper" way.

sixspeedfirebir

Well I should be able to do all that myself. If not I have an Uncle who might as well be a mechanic. I might drop the muffler/rear/fuel tank anyway and go ahead and get a good cat-back while I'm at it.

Is there any way to check the fuel pump to see if its going bad or not?

Spinner

Fuel pump is the only noise making device in the rear of the car.

WestCoast96Z28

Never thought about this..but I've heard the same high pitch whistling in the back as well. I also assumed it was the rear speakers, so never really worried about it.

So, don't know much about the fuel pump in our cars. Is it in the tank or outside? I'm guessing outside since Capn Pete's recommends pulling it from the top. Can someone tell me where fuel sending unit is located or better yet some pictures of where to cut in the trunk?

Spinner

Do a search for it, theres plenty of guides out there. Definetly do it from the top though

s3gulit

Depending on when u last did basic preventative maintenence you might want to change the fuel filter to just make sure thats not the problem. When i bought my 96 silverado this summer the truck had an irrtable whine coming from the fuel pump (easy to tell because its right behind the cab). I decided to check everything over when i did my oil change in a couple weeks after and changed the fuel filter...previous owner never changed it...86,000miles and not one fuel filter change. Fuel pump was working so hard to push fuel through the filter it was making the terrible "whine". Soon as i replaced it it became more of a tolerable noice and i could barely notice it.

Just an inexpensive idea to see if it would help (like $15) for a fuel filter.

Dave

Capn Pete

The pump is inside the gas tank, and I'm pretty sure that the sending unit & pump are all 1 complete assembly.....you can't just buy the pump, you're buying the whole works.

Spinner

Uh, no. You buy the pump. The pump is in the tank, inside the fuel bucket, and easily replaced. 2 hour job if you cut a door from the top

sixspeedfirebir

So is there any way to check it before I go tearing around back there?