I'm currently trying to fix my friends 89 RS with the 2.8l multi-port. He's experiencing a problem starting his car when the engine has come up to temp and he attempts to start it again after a shutdown. It's not as pronounced when it's cold but it's still not as quick as it use to be. Upon initial testing of the fuel pressure at the fuel rail with the ignition on but the engine off I noticed that the pressure would only build up to about 25psi and then go to zero in about 5 seconds when the fuel pump turned off after the initial two seconds. I did the test again but this time clamped off the return line from the regulator to the tank when the pressure was at its peak and the pressure still died off. I then did the test again but clamped off the supply line from the pump to the fuel rail the pressure stayed. My friend just recently had a shop change his fuel pump so I thought that the check valve in the pump was no good. I took the car in and the mechanic told me that the pumps for the multi-port camaros don't have a check valve in them and that my problem is more than likely somewhere else. My question to you is a) is this true about no check valve in the pumps or at the pumps? b) shouldn't I be getting a higher initial pressure when I first turn the key on and energize the pump (approx. 40-47psi) and c) why is this problem more pronounced when the engine is hot rather than when it's cold. Do I have multiple problems here? Any info would be greatly appreciated. Thanx.