1. Verify Fuel Pump Power Directly:
* Locate the fuel pump relay: Your owner's manual will show the location. It's a small square or rectangular box in a fuse box (under the hood or inside the cabin).
* Test for power at the fuel pump relay: With the ignition key ON (but not cranking), use a test light or multimeter to check for power at the relay's terminals. The specific terminals to check vary by vehicle year, but your owner's manual or a wiring diagram will indicate which terminals should have power with the ignition on. If no power, the problem is upstream of the relay.
* Test for power at the fuel pump itself: This requires accessing the fuel pump, often located under the vehicle. This is more involved and may require disconnecting fuel lines (be cautious, as fuel is flammable). With the ignition ON, test for power at the fuel pump's electrical connector. If no power here, the problem is in the wiring between the relay and the pump.
2. Check the Fuel Pump Circuit:
* Wiring harness: Inspect the wiring harness running to the fuel pump for any damage, corrosion, or broken wires. Pay close attention to areas where the harness might rub against the chassis or other components.
* Ground connection: A poor ground connection can prevent the pump from receiving power. Trace the ground wire from the fuel pump and ensure it's securely connected to a clean, unpainted metal surface.
3. Consider the PCM (Powertrain Control Module):
* PCM issues: The PCM controls the fuel pump. If the PCM is faulty or has a programming problem, it may not be sending the signal to activate the pump, even if everything else checks out. This requires more advanced diagnostics, potentially using a scan tool to read diagnostic trouble codes (DTCs).
4. Ignition System:
* Ignition switch: A faulty ignition switch may not be sending the correct signal to activate the fuel pump relay.
* Neutral Safety Switch (automatic transmission): If it's an automatic, this switch prevents starting unless the transmission is in Park or Neutral. A faulty switch can interrupt power.
Important Considerations:
* Safety: Working with fuel and vehicle electrical systems can be dangerous. If you're not comfortable performing these checks, it's best to take your truck to a qualified mechanic.
* Year and model: Providing the year and model of your Chevy 1500 will help in finding more specific troubleshooting information. Wiring diagrams and relay locations vary significantly between models.
By systematically checking these areas, you should be able to pinpoint the cause of the problem. Remember to consult your owner's manual for specific diagrams and locations for your truck.
