I have a 2000 Silverado 1500 5.3, the problem I'm having is the fuel pressure shows 50 PSI on start-up but as the engine warms up the fuel pressure drops to 10 PSI and the truck dies. I thought the cause of this was a bad fuel pump, so I took it to a shop, and they diagnosed that I needed a new fuel pump, so I got a brand new one and installed it which made it run fine for about a week but now it's back to how it was except it hasn't died yet. Does anybody know what I can do to fix this? Thanks.

 

did they change the fuel filter when the pump was changed? If not, change the filter (it must be changed when the pump is replaced or it will void pump warranty) and check the fuel pressure. If the pressure is still low; check for battery voltage at the pump and good ground at the pump.

 

I just changed the fuel filter and checked pressure and it was still low so I checked voltage and ground and both are good. I’m not sure what to do now.

 

Will this only happen while driving or will it also happen at idle?

Are there any codes?

With a fuel pressure gauge attached, Check the current draw on the fuel pump circuit for the amount of time it takes for the pressure to drop.

Typical pump draw is about 10 amps.

If the current decreases in proportion with the pressure, it’s likely that the wiring has a partial open/high resistance. Further diag/inspection will be needed to isolate the problem area.

If the current increases in proportion to the pressure drop, it’s likely a restriction in the fuel supply or return lines is the cause.