97 Express 3500 with 454 ci engine. Replaced the fuel pump and pressure regulator and now it starts intermittently. Sometimes it won't start but I let it sit for a half hour or so and it starts. Sometimes I get no hum from the pump, I can bang on the fuel tank and it kicks in and starts. I had it scanned and showed code for throttle positioning sensor. Any help would be appreciated.

Thanks

 

try swapping the fuel pump and starter relays. They are the same. If it improves there is your issue. If however the new pump is faulty.....( was it new or a used part?) Then it might need doing again.....
I have heard stories of new pumps only lasting a few months...which sucks for sure.
Replace the tps if its bad. Computers don't work well with faulty input readings.

 

454,, that thing must haul ***... good luck with your repair.