Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
- The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
- DO NOT start the engine.
- Ignition ON, command the fuel pump relay ON with a scan tool and observe the fuel pressure gage while the fuel pump is operating. Verify the fuel pressure is between 301-347 kPa (44-50 psi).
- If less than the specified range, remove the fuel tank and test for any of the following conditions:
IMPORTANT:
- Restricted fuel feed pipe
- Restricted or plugged fuel filter
- Restricted or plugged strainer
- Stuck or binding fuel level float
- Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
If all conditions test normal, replace the fuel pump.
- If greater than the specified range, replace the fuel pressure regulator. Test again for fuel pressure between 301-347 kPa (44-50 psi). If still greater than the specified value, replace the fuel pump.
- If greater than the specified range, replace the fuel pump.
- Verify the fuel pressure does not decrease to less than 147 kPa (21 psi) for 5 minutes.
- If greater than the specified range, perform the following procedure:
- Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief .
- Install the J 37287 between the fuel feed pipe and the J 42982 . See Special Tools .
- Open the valve on the J 37287 . See Special Tools .
- Ignition ON, command the fuel pump relay ON with a scan tool and bleed the air from the fuel pressure gage.
- Close the valve on the J 37287 . See Special Tools .
- Verify the fuel pressure does not decrease to less than 147 kPa (21 psi) for 5 minutes.
- If the fuel pressure is less than the specified range, locate and replace the leaking fuel injector.
- If greater than the specified range, perform the following procedure:
- Ignition OFF, remove the J 34730-1A and J 42982 . See Special Tools . Refer to Fuel Pressure Gage Installation and Removal .
- Operate the vehicle within the conditions of the customers concern while monitoring fuel related parameters with a scan tool. The scan tool parameters should not indicate a lean condition.
- If the scan tool parameters indicate a lean condition, test for a restricted fuel feed pipe, restricted fuel filter, or poor connections at the harness connectors and ground circuits of the fuel pump. If all test normal, replace the fuel pump.
- If the fuel system components test normal, refer to Symptoms - Engine Controls .
IMPORTANT:
The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.