Screeching sound coming from rear of the car - sound clip.

**Tataocb** · 03-15-2016, 08:45 AM

I bought a 98 Trans Am with 148k miles about 7 months ago. The car has been parked since then, I would take for a 1 mile drive every couple of weeks, but that was it. I got a Flowmaster 80 muffler from a friend for like $20 and had it installed on Saturday.

It was a twenty min drive to the exhaust shop at around noon. I'm in Houston, and the weather was in the high 70s to low 80s. They removed the stock muffler and installed the flowmaster in about 35 min, we started it up, and it sounded good. The drive home was about 25 min where half of it was in the interstate and the other half in smaller roads. When I got home (close to 2 pm), I noticed this noise coming from behind the rear wheels. If I stood behind the car, it sounded as if it was coming from the center. I thought it might have been some sort of exhaust leak or maybe the muffler was bad. I researched online and noticed many people say it might be the fuel pump. I noticed the noise was heard even when I turned the key, before starting the car. So it led me to believe it might have been the fuel pump as it was priming. 5 or 6 hours later, I went back to the car, fired it up, and could not hear the noise any more. I tried it on Monday night and I could barely hear it at idle while standing next to the rear tire.

I don't know if it's coincidence that this happened with the change of the muffler, or maybe I hadn't paid attention to it before or heard it since my drives were really short and I have only owned it while the temps have not been that high. I mention the temperature because based on what I read, higher temperatures make it more likely for the fuel pump to start making noise. I recorded the noise as I turned the key (so you can hear it when it is priming), and then at idle. It is that high pitched screeching sound. This recording was made right after I got back from the exhaust shop. At the end of the recording, I had my phone right behind the rear license plate.

I cannot include attachments, so I uploaded the audio file. Here is the link:

Vocaroo | Sound Clip

Thanks for any help you guys can provide.

***SMWS6TA*** · 03-15-2016, 10:40 AM

Yup that's the fuel pump. It may be on it's way out, it may be because you are low on gas. Try to keep an 1/8 or more in the tank, try not to run it low. The fuel cools the pump, strange, I know but it's true. Also in case you didn't know there is no "Low Fuel" light on the 98's, so if you see it near you best be heading to a gas station.

Now if it does go out don't run out and get one from the parts stores. Racetronix makes a damn good pump that is easy to install and is cheaper then getting an OEM fuel pump.

**Tataocb** · 03-17-2016, 05:29 AM

Thanks for confirming my suspicion.

I will try the suggestion in this post (using Marvel Mystery Oil), and see if the noise goes away, before looking into changing the fuel pump.

Fuel Pump Whine?

**0rion** · 03-17-2016, 11:15 AM

yeah....won't hurt to try. I would probably have a plan in place for a new pump though. Like Scott said......that racetronix kit is the way to go.

**Tataocb** · 03-18-2016, 05:29 AM

Originally Posted by 0rion

yeah....won't hurt to try. I would probably have a plan in place for a new pump though. Like Scott said......that racetronix kit is the way to go.

Yeah, I already started reading up on how to change the fuel pump. I know it is something that will have to be done eventually.

**0rion** · 03-18-2016, 04:09 PM

it's not that bad......the biggest pain in the ass is just getting the tank down. You basically drop that rear as low as you can get it and pull the last section of exhaust off. Get the car plenty high and wrangle that tank out. The 98's have a metal filler neck which makes that tricky as hell but you just have to keep twisting that tank to find the right angle and the neck will come out. After I got my tank out I took a cut off wheel and opened that hole up for the filler neck and painted it. No issues getting that puppy back in.

***SMWS6TA*** · 03-20-2016, 05:28 AM

Originally Posted by 0rion

it's not that bad......the biggest pain in the ass is just getting the tank down. You basically drop that rear as low as you can get it and pull the last section of exhaust off. Get the car plenty high and wrangle that tank out. The 98's have a metal filler neck which makes that tricky as hell but you just have to keep twisting that tank to find the right angle and the neck will come out. After I got my tank out I took a cut off wheel and opened that hole up for the filler neck and painted it. No issues getting that puppy back in.

That is option 1...

Option 2 is make a cutout panel. Basically you cut out a section of the body right above the fuel pump. No dropping of the tank. YOU JUST HAVE TO BE EXTREMELY CAREFUL SO THAT YOU DO NOT DAMAGE THE TANK & FUEL LINES. It's not to difficult just need to pay attention to your depth of your cut when using a cutoff wheel.

**Tataocb** · 03-30-2016, 07:11 AM

I took the car out for a 30 min drive this weekend close to noon, and as I was coming back home I heard the noise again. So I will start planning the fuel pump replacement. Is the racetronix pump the same as a walbro pump? I have seen some sellers on ebay offering what looks like a walbro GSS294M pump with a racetronix harness.

**35th-ANV-SS** · 03-30-2016, 07:24 AM

Walbro is the pump mfg for the Racetronix kit.

***SMWS6TA*** · 03-30-2016, 07:29 AM

Racetronix uses a Walbro pump or at least it was one that came in.

**raynor139** · 03-30-2016, 09:05 AM

Racetronix also has a wire harness kit you can buy for the pump that connects directly to the alternator. That way you get the right voltage all the time. Not really necessary if your just going to leave the car stock but if your going to add more hp upgrades worth it for the higher fuel demands.

I bought there complete replacement kit also. When I did it everything was 13 years old so figured better safe then sorry.

**Tataocb** · 03-30-2016, 11:43 AM

I think I will just buy the kit with the pump and the harness. Is it worth adding the negative battery kit?

Do you guys think a 7" grinder can be used to cut the trunk panel? Or would it be too big?

***SMWS6TA*** · 03-30-2016, 12:32 PM

Yes on the kit...

Grinder....depends on just how good you are at controlling it. The sheet metal is only a 1/16th of an inch. Just be very careful

**Tataocb** · 04-29-2016, 10:41 AM

So what do you use to put the sheet metal back in place?

***SMWS6TA*** · 04-29-2016, 10:46 AM

I added a couple of sheet metal pieces and rivet to the original piece to act like a support then used duck tape to seal it. No one sees it and the tape while sealing the cabin lets you access it quickly when needed. Which I've been needing to do lately. I'll snap a pic and post later.

**Tataocb** · 05-05-2016, 01:35 PM

Thanks. I am interested in seeing how you have it setup. I ordered the fuel pump today, so I might get started this weekend if it's delivered by Sat.

**Tataocb** · 05-20-2016, 08:43 AM

I finally had time to get started with the wire harness last night. It looks so easy in the instruction manual. When working on the actual car the space felt very limited in my case, working with only a couple jack stands. I woke up with a little neck pain this morning from being under the car

I hooked everything up in the back, and routed the harness like mentioned in the manual (alongside the brake lines), but did not have time to hook it up to the alternator.

***SMWS6TA*** · 05-20-2016, 10:32 AM

Make sure you route it under the heat shields or you'll cook the wire on the headers.

**Tataocb** · 05-23-2016, 06:55 PM

Here are some pics of how it goes into the engine bay. The first pic is taken from the top side, you can see the brake booster in the top right corner. The second one is taken from underneath. Is that too close to the exhaust? I don't think I can get in there to remove the 2 nuts in the second pic.

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**Tataocb** · 05-23-2016, 08:13 PM

I was able to get the wire inside the heat shield....sort of. I wasn't able to remove the shield from the lower bolt after taking the nut off, so I had to go around it. It takes a lot of patience to remove those nuts when the front of the car isn't lifted.

Now, how the hell do I get to the rear of the alternator? The instructions seem to show an alternator that has been removed from the engine, because I don't see any space to get two wrenches in there using both hands at the same time.

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