I have a very strange problem. I have a Holley in tank pump. After the cars been running for a while the pump lets out the loudest and most anoying shreaking high pitch scream. There is no noticeable effect on performance. Ive noticed that the fuel tank is warm to the touch right up to the top of the filler neck. I have a Flowmaster dual chamber fed by edelbrock headers. This muffler gets real hot and is just under a skinny factory heatshield. Is it possible that the exhaust is heating up my tank? The preassure in the tank when the pump is screaming is enourmous. I can actually hear the tank poping and it has fired my fuel cap across a parking lot when i opened it. This is not normal. Its venting. I checked through the use of the GM service manual. I even took the charcoal canister out so it would always vent. I really need some ideas here please

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1987 T/A GTA 5.7L, Bored .020 and ported for .202 valves, edelbrock headers, flowmaster exhaust, JET STAGE II chip, Comp CAM, Adjustable fuel pressure, Airfoil, K&N filter, B&M stage 2 shift kit, and a home depot ram air(Hey it looks good and it works)