Fuel Pump: Testing and Inspection

Fig. 3 Installing test relay 5170:

1. Switch ignition on and install test relay 5170 to simulate ignition system pulses, Fig. 3. Listen at rear of vehicle to determine if pump is running.
2. If pump does not run, check fuses No. 5 and No. 7. If fuse is blown check circuit for shorts and replace blown fuse.
3. If fuses are OK, check for voltage at fuel pump by measuring at connection in trunk. If voltage is available, check for a defective fuel pump, bad wire between connection in trunk or a bad ground.
4. If no voltage is detected, check for voltage at terminal 87 on main relay (yellow wire). If voltage is available, a defective connection between main relay and fuel pump is indicated.
5. If no voltage is detected, check for voltage at terminal 30 on main relay (red wire). If no voltage is detected, a defective connection between main relay and fuse No. 7 is indicated.
6. If voltage is detected, check for voltage at terminal 15 on main relay (blue/red wire). If no voltage is detected, a defective wire between relay and fuse No. 5 is indicated.
7. If voltage is available, ground main relay (terminal 31-black wire) and check if fuel pump runs. If fuel pump runs, a defective ground connection is indicated.
8. If fuel pump does not run, check for pulsating voltage at terminal 31b on main relay (white/red wire). If voltage is available, a defective relay is indicated. If no voltage is detected, check for a defective wire between main relay and ignition coil, a defective test relay or defective ignition system.