I have a 3.1L Lumina that has developed an odd noise (withen the last week) that I can't exactly pin down to were it is other than the right side of the car. For a while it didn't affect anything at all however while trying to locate it this weekend the car now constantly has the noise (best discribed as a high pitched weee sound) and while the car runs fine at lower RPM when you step on the gas hard it seems like it is being restricted and stutters.

I honestly think it's a bad cat which sucks since it's all welded together and I don't know how to fix that problem myself without taking it to someone else to repair. So I want to know if it might be something else other than the cat so that I don't needlessly fix that and still have the same problem afterwards.

There is no way to diagnose noises form here, if you are revving the engine in neutral you may be hitting the rev limiter, not sure on a 91 whether this is in place though. The whistle would be heard in the exhaust if the cat was blocked, drop the pipe down and see what happens.

Would a stuffed up cat cause this as well? While driving the car it will run fine and even accelrate pretty evenly so long as you don't apply more than a 1/3 of the presure on the gas peddle once you try to go beyond that the car hesitates and will not accelerate at all. Could this instead be a fuel pump issue?

Could be either get the FP tested, no?

Since my roommate got home I was able to test the flow rate of the exhaust and it's definitely not clogged. Also found that the noise is coming from the rear passanger side of the car, so more than likely it's the fuel pump making the noise. I'm thinking that I would have to take out the Fuel pump to test it so I haven't done that yet.

Test it in the car using a FP gage, no?

Had to look it up and now that I know what I need I'll go check that out.

Ok I checked the fuel pump pressure and it's way high at 43psi (supposed to be 26-32psi for a throttle body injection and other engines before 97) when I just run the fuel pump it also doesn't make the noise at all when I'm just running the fuel pump.

The book says to replace the regulator if this is the case but doesn't exactly show me where it is. It also says to check for pinched or damaged return lines and I'm going to change the fuel filter as well before getting the regulator.

Does that sound about right?