INSTRUCTIONS TO INSTALL FUEL PUMP ON 1989 CORVETTE

https://www.corvetteforum.com/forums/c4-tech-performance/3059317-89-fuel-pump-relay-and-fuse-problem.html

Fuel injectors cleaning ! How to Diagnose Test and Clean Dirty Clogged or Bad Fuel Injectors

Check your fuel pressure it should be 40-47 with the key and engine off and 30-44 with engine running.If its not within these specs then replace the fuel pump and filter.

The only part that would come to mind after all of this would be the fuel pump relay. This is located on the fire wall on the drivers side of the car. When that goes bad it does not allow for adequate fuel to cycle through.The other thing would be timing. You need fuel air and spark for the vehicle to fire. After all the test and after replacing the fuel pump relay. I would do a compression and a leak down test. Are you sure that the timing did not jump a gear? You can also look and test the IAC (Idle Air Control) or the MAF (Mass Air Flow Sensor). Also do a test to check fuel pressure. The last Corvette that I worked on personally that had this issue it turned out to be the Fuel Pump Relay. Good luck let me know if you have any further questions.

It is located just to the right (toward the passenger side) of the brake master cylinder/booster.

is the pump inside of the fuel tank ... or outside.. if inside the tank usually has to be taken out if the pump is an external electric pump it is somewhere along the fuel line if it is mwchanicle it is on the engine block

My first guess would be the fuel pump. Alot of defective pumps will operate until they warm up.

About an hour, Open the lid where you put the fuel, there are four screws that you have to remove, remove the lid, pull the rubber boot out and there is the pump sending unit. remove the eight or ten bolts and pull the unit out. replace the pump and install in reverse order. These are the easiest ones I have done. You can do it.
Randy

i want to give you the right answer but the only thing i think of is the mass air flow sensor.

The 5.0L injector is sized to deliver approximately 4.05 milligrams of fuel with a 2.5 millisecond pulse or 18.13 lbs per hr at approximately 36 PSI. The 5.7L injector is sized to deliver approximately 4.83 milligrams of fuel with a 2.5 millisecond pulse or 23.92 lbs per hr at approximately 43.5 PSI. This information is typical for all manufacturers and flow rates will vary slightly even between identicle injectors.
Good luck and hope this helps.