My fuel pump is not kicking on when I turn on the ignition. I replaced the pump but it still isn't working. I checked the switch under the dash and it is plugged in. I'm not exactly sure where the relay is under the hood. What else can I check to diagnose the problem?

 

Start with the fuses and work from there, you mentioned the inertia switch being plugged in, the red button was down? Pump has to run 2-3 seconds on initial ignition on, then should continue to run when oil pressure is established. What year is this truck? Helps on wiring diagrams.

 

The fuses are all good and I can hear the fuel pump relay switching when I turn the ignition on. It's a 90 that originally came with a 4.9 but now has a carbeurated 5.0.

 

Carburated? Sure hope there is one big pressure regulator between pump and carb. Carbs work on 3-5 PSI.

 

Yup, it's got a fuel pressure regulator.