I have a 1992 Z-28, 5.7L TPI. After driving in stop-an-go traffic and it is hot outside, the fuel tank will make a whining noise. It is worse when there is less than a full-tank, but it does it regardless of the fuel quantity. This problem has been happening for 10 years, but now, it occasionally results in the engine stalling. I have never really figured out why it whines like this. So far, I have replaced the fuel pump, pulsator, charcoal canister, evaporative canister valve, fuel pressure regulator and the pressure relief valve that mounts on the rear axle. Today, after driving in 100+ temperatures, as it was whining, I pulled over and put the car in park and slowly opened the gas cap. Fuel started coming out of the filler neck. Then I could hear the pressure relief valve click (don't know if it was opening or closing) and the engine stalled. It would start again, but I had to wait 10 minutes. Any input? Thanks in advance.

After spending a few hours reading other posts about "boiling" fuel tanks, I think I have a direction to go. I installed a Thrush/CVX muffler back in 1993 and I'm thinking that as the insides of the muffler have decayed, more heat is able to reach the exterior. The gas tank is directly above the muffler.

Can anyone suggest a good (inflammable) material to wrap the muffler with?

i have the similar problem and also cut off my flow masters that were right under the fuel tank reguardless of the heat sheild.

Thanks. I bought a heat shield today. I will post back with the results.

I installed the heat shield and drove it for two days in 110 degree heat. I am happy to report back that the shield solved the problem. Thanks to the information I read in forum members' prior posts, I was able to resolve a problem that probably the dealer couldn't have fixed without throwing thousands in parts and labor at it.