AJ88

I just recently purchased a 1997 Z28 with 63xxx miles on it. After driving it a few days I started to notice a buzzing/whining noise coming from the rear end. At first I thought it was a speaker issue but I got out and heard it from under the rear near the exhaust. Any ideas? I made a YouTube video

https://youtu.be/wWwGEqLdLuo

VChula

It is most likely the fuel pump.

AJ88

Great...

VChula

Doesn't mean the pump is bad.

I hear the pump in my 1996 all the time - especially when the hatch compartment cover flap is in the down position.

AJ88

It's pretty loud right now, just noticed it yesterday. Think I should look into replacing the fuel filter, or any other ideas to try?

Injuneer

Check the fuel pressure. Should be in the range of 41-47 PSI at idle, with the vacuum compensation line off the fuel pressure regulator. When you reattach the vacuum line, pressure should drop to about 8 PSI below the “no vacuum” pressure.

Tape test gauge to windshield, take it out on the road, under full load. At WOT, up to 5,000+ RPM, pressure should not drop below 40 PSI.

From Shoebox

http://shbox.com/1/fp_reg.jpg


Best LT1 reference site on the internet

4th Gen LT1 F-Body Tech Aids

AJ88

Thanks, I'll try to get around to that this weekend.

DrewHMS97SS

A fuel filter wouldn't hurt though. Do you know any of the history of the car? if the car sat with fuel in the tank for long periods of time, there could be rust in the tank. My car sat for the better part of 7 years with the same gas (with stabilizer), and I had the tank rust out. The sock at the bottom of the tank had dissolved.

If the car sat, you can check for rust in the tank by cutting the old fuel filter open with a hack saw (don't use power tools). If there is rust in the tank, it is most likely making your pump work harder, which can make an audible difference.

AJ88

That is very possible. I don't know the previous owner personally, but from the auto check report it was only driven around 4500 miles over the past 8 years. I put a complete fuel system cleaner in the tank yesterday to see if that would help any.

DrewHMS97SS

When I got mine back on the road, I was able to run about 250 miles before the pump took a dump. The fuel pressure test will tell you if the pump is keeping pressure, and the regulator is good, but not if there is an issue in the tank. Filters are only about $20, so without knowing the history of the car and the noise you are hearing in the tank, I would definitely replace the filter and inspect the new one (worst case you have to replace the filter again if something has to be done with the tank).

I can tell you from personal experience, that the fuel pump/tank process in the 97 is painful. This is mainly to do with the solid filler neck. The tank has to drop down at an awkward angle which requires the rear end to be removed from the car. Some have cut a hole above the tank to swap the pump, I would advise against this as it is a structural part of the car.

Before we go down that path though, change the filter and inspect for rust and do the pressure test. Here is my current logic:

Rust in the filter: tank comes out
Low fuel pressure: tank comes out

AJ88

Thanks, sounds like a solid assessment. I got a fuel filter today, gonna check the pressure and see about replacing the filter this weekend.

AJ88

*Update

Fuel filter replaced and seemed to run fine. Fast forward to today and it stalled twice and fuel pump is near dead. Very little pressure, enough to start after about 10 seconds of turning the ignition. So the fuel pump is getting replaced...

DrewHMS97SS

Did you cut open and inspect the old filter?

Since you are doing the pump, you will know if the tank is the root problem after you get it out.

The filler neck is the hardest thing to clear when taking the tank out, which requires the rear end to be out of the car. When doing my plastic tank swap a few months ago, I spent a ton of extra time that could have been saved by just moving the rear end vs just dropping it down. The other item that can be a pain is the exhaust, which is completely dependent on what is on the car. Mine had flanges added before the axle, so I only had 6 bolts to remove the mufflers. Let us know if have any questions on pulling the tank.

Take a look here for a one stop on the pump if you don't already have a source: Shop by Category - Camaro - 93-97 Camaro - Fuel Components - Fuel Delivery - Page 1 - Hawks Third Generation

I ran the Racetronix setup originally and had great performance (until rust and old gas killed everything). I am running the Areomotive now, which on paper performs better, but is not as easy an install. If the tank is rusted and the sender is in bad shape, there is a full sender and stock pump ready to bolt in here too.

Before any decisions are made, I would pull the tank and see where you stand.

AJ88

Tank was in good shape, after replacing fuel pump, fuel filter and filling up with a fresh tank of gas all runs better than ever. Thanks for all the input.

DrewHMS97SS

Great news! You make it seem like it was a cake walk =D