Circuit/System Testing

Fuel Pressure Low

1. Verify the following conditions do not exist:
   • Poor component electrical connections: Fuel Pump - Chassis Ground
   • Poor component electrical connections: Fuel Pump - Electrical Connector
   • Fuel Feed Pipe - Leaking/Restricted/Visible Damage
   • If a condition exists 

     Repair as necessary

   • Go to next step: If no conditions exist 
2. Test or replace the component: G12 Fuel Pump

Fuel Pressure Leaks Down

1. Ignition/Vehicle - Off
2. Relieve the fuel system pressure. - Refer to: Fuel Pressure Relief
3. Install the special tool: EN-37287 Fuel Line Shut-Off Adapter @ Fuel Feed Pipe
4. Open the valve on the tool: EN-37287 Fuel Line Shut-Off Adapter
5. Ignition - On/Vehicle - In Service Mode & Engine - Off
6. Perform the scan tool control function: Fuel Pump Enable - On and Off
7. Close the valve on the tool: EN-37287 Fuel Line Shut-Off Adapter
8. Verify the scan tool parameter: Fuel Pressure Sensor = Pressure drops less than 34 kPa (5 PSI) within 1 min.
   • If the pressure drops 34 kPa (5 PSI) or greater 

     Locate and replace the leaking component: Q17 Fuel Injector

   • Go to next step: If the pressure drops less than 34 kPa (5 PSI) 
9. Test or replace the component: G12 Fuel Pump

Fuel Pressure Drops Off

1. Verify the condition does not exist:
   • Poor component electrical connections: Fuel Pump - Chassis Ground
   • Poor component electrical connections: Fuel Pump - Electrical Connector
   • Fuel Feed Pipe - Leaking/Restricted/Visible Damage
   • If a condition exists 

     Repair as necessary

   • Go to next step: If no conditions exist 
2. Test or replace the component: G12 Fuel Pump