I recently purchased a '88 Trans/Am 350 TPI automatic. Really nice car but with a problem. When the fuel gets to about a 1/2 tank the pump begins to whine while driving. After the car is shut off it releases a really high pitched whine for about 20 minutes. If I open the gas cap the noise goes away. The person I bought the car from said the vent line to the pump was plugged up. He said that he blew air threw the line and in the engine bay behind the distributor there is a white spot of "goop" that was supposedly blown out. I can't seem to find anyone who knows what the white goop could be. I'm pretty sure I have to replace the fuel pump, and possibly have to clean and/or vat the tank. I'm not sure, however, if I need to do anything else. Dropping the tank is a big pain and I don't want to do it twice. Any help would be appreciated.

 

Well, you might want to look at something far easier to replace first. There is a mushroom shaped tank vent that is attached to a bracket in front of and to the left(left meaning drivers side of the car) of the gas tank on the drivers side underneath the car. If you jack the drivers rear side of the car up and scoot under, you should find it coming from one of the hoses from the tank. It took me a few minutes to figure out where it was, but I slid under from in front of the rear tire a bit and looked around. It's been a while since I replaced it, but it is about in that area. It was attached to a rubber hose that went to the gas tank I believe. I think it's somewhere in the vicinty of the shocks, but I may be remembering the spot incorrectly. It attaches to a metal bracket using 3 or 4 plastic bendable tabs.

Yeah, I know my descriptions are a bit off, but I can't think of what to call them now. Anyway, a couple of those plastic pieces were broken so it slid out of the metal bracket easy, but yours may be intact so it could use some force or pushing up on one or 2 of those tabs with a screwdriver. Other than just looking at it to get a feel for where it is, you should prolly leave it alone until you order a brand new one. I happen to have the part number here too, somewhere, right on the original box top. I'm keeping it due to the fact that the part is impossible to find the number for, and all that. Hmmm, let's see now...

Yeah, that only took 10 minutes. Anyway, the part number is 10033125. Listed as a valve assembly. Now, I will not guarantee that this will fix your problem, but, seeing as yours was exactly the same as mine with the added bonus of the gas tank making loud banging noises within 30 minutes of shutting it off and occasionally while driving, it SHOULD solve it. This part is for a 91 Trans Am, but should be the same for a number of years and for Camaros. Not sure about earlier years, 82-85, 86 or whatever, but... I got it either from newgmparts or gmpartsdirect. I forget which, but only one of those 2 places listed the part at all in either case.

My original valve "looked" reasonably fine, other than the broken tabs, but as soon as I replaced it, the noises and tank collpasing and expanding noises went bye bye.

Oh, here's a link to a picture of the valve vent.
https://www.thirdgen.org/forums/atta...082705-003.jpg

 

Oh, one other thing that may be causing the problem is the evaporative canister vent valve. It's a lil UFO looking thing usually very close to the charcoal canister. It will have one hose going in from the tank and 2 going out to the canister. That one is easier to replace then the vent valve, and will likely be stocked at any parts store. I also replaced my charcoal canister at the same time, but that's just me. If you're yanking off those hoses to replace the canister valve, you may want to replace them as well since they are likely in crummy shape after 20 years. Mine were, that's for sure.

 

I've already decided to tackle the fuel pump but I think I will tackle the other 2 items you mentioned as well, just to be on the safe side. Thanks.

 

If you are going to drop the tank you should also check out (if it exists in your fuel tank) the short rubber connection hose that is between the fuel pump and the fuel hard line that sends to fuel OUT of the tank (under pressure). On my 1989 Camaro that piece is 1.75 inches long. It is well worth replacing if you have the original in place. Mine became soft over the years and developed a crack. It was acting like a 'low set' pressure valve. With no pressure built up it would send a nice volume to an empty fuel tank I placed down near the fuel filter. But when the fuel system was hooked up properly and the pressure built up it would 'leak' most of the fuel back into the tank. As a consequence the fuel injectors (TBI system running at about 11.5 PSI) would not get adequate pressure to spray the fuel out of the injectors. So the engine just would not start and continue to run. I replaced that short 3/8 '' ID hose (in my 1989 Camaro 305 FI Vin E TBI fuel tank) and now the engine has plenty of fuel pressure to the carburetor. That short piece of fuel hose should be like NAPA H213 which is 3/8 '' SPECIAL 'submersible' hose that meets a SAE 30R10 rating. It costs about $1.00 per half inch. I had to purchase a minimum of one foot so that cost me $24.00 (ouch). But I would strongly suggest (if you are pulling the tank that you change that connection hose (if you have one) and especially if it has never been changed before.

And you should probably replace the fuel tank seal (a large O ring type) while you are dealing with the fuel sending unit. I suspect that when you remove the fuel sending assembly you will find that the rubber seal (O ring) should be replaced rather than re-used.

 

I replaced the pump with an A/C delco pump that came with a new o-ring and that short rubber hose. My car had a pulsator, but I removed it and I used that short rubber hose. My o-ring was shot so it was a good decision to do the pump. My fuel pump strainer was in two pieces at the bottom of the tank so I'm really glad I did the pump. I also replaced the "valve assembly". Mine didn't seem to work the best when I tested it and the new on performed a lot better. In the end the car ran better but I still suffered from a whine in my gas tank after I shut the car off. This being an original Californis car it had all emissions stuff for that state. I went and got a vented gas cap and now my problem is gone. I'm glad I changed everything, my car definately needed it. Being in a non-emissions state the vented cap worked well. The only other possible cause I could think of would have been the charcoal canister. I ordered the vent valve but it hasn't came yet. Once it does I'll replace it and try the unvented gas cap versus the vented. Either way I'm in good shape. Six hours worth of labor, but I had all the tools and the procedure went surprisingly well. It was worth the effort and the $550 bucks I would have paid the dealship to do it and that was not including parts.