Here is a part of a Q&A I found on another website.

Q I have a '99 Chevy Suburban 1500 which has been having a fuel problem. The car will crank but not start. Hitting the tank with a rubber mallet from below while cranking the car will start it. It will then run perfectly and then it will happen again whenever it wants. This problem happens when the tank is full or empty. Is this an ethanol or fuel pump problem?
A Who's your co-driver? Or do you have a very long arm? On a more serious note, how loud is the fuel pump when the engine does run? Can you hear it over engine or road noise? If so, the fuel pump is probably worn.


I wonder if my fuel pump is giving me the "MULITPLE ENGINE MISFIRE" trouble light I am getting at high RPMs? Mine is a 99 C1500 with 5.7.

 

Change the fuel pump, it is bad and very likely the cause of the DTC's, too little fuel volume at high RPM's will lean out cyclinders enough to set a code.

 

Change the pump or you will be walking. I would only buy the AC Delco brand pump. Cost a little more but worth it.