Vehicle: 2003 Chevrolet Express 1500 Base 5.3L, V8, MFI, OHV, VIN T, GAS
Customer Concern: No start, no fuel pressure. Replaced the fuel pump and relay, still no fuel pressure.
Tests: 1. Remove the fuel pump relay and check for power at one terminal from fuse 12 (20 amp).
2. One terminal should get 12 volt power when the key is turned on for about 2 seconds and also when the engine is cranking. This is from the Powertrain Control Module (PCM) pin 9 of the Green connector, a Dark Green/White wire.
3. One terminal should be a good ground to G102 and the other terminal should have continuity to the pump. Putting 12 volts on the pump terminal should show 12 volts at the pump with the pump plugged in. If the voltage is low at the pump there is a wire problem between the relay and pump, inspect the connections under the under hood fuse block.
4. Verify the pump ground is good and the frame ground to the battery is good.
- Potential Causes: Under Hood Fuse Block Wiring
- Fuel Pump Ground Wiring
- Frame Ground
Confirmed Fix: Repaired Frame Grounds: Added a ground to the frame.