Circuit/System Testing
- 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 380-427 kPa (55-62 psi).
- If less than the specified range, remove the fuel tank and test, inspect, and repair the items listed below. If all items test normal, replace the fuel pump.
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 greater than the specified range, replace the fuel pump.
- Verify the fuel pressure does not decrease greater than 34 kPa (5 psi) in 1 minute.
- 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 fuel rail.
- Open the valve on the J 37287 .
- 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 .
- Verify the fuel pressure does not decrease greater than 34 kPa (5 psi) in 1 minute.
- If the fuel pressure drops, locate and replace the leaking fuel injector.
- If the fuel system test normal, replace the fuel pump.
- If greater than the specified range, perform the following procedure:
- Relieve the fuel pressure to 69 kPa (10 psi). Verify the fuel pressure does not decrease greater than 14 kPa (2 psi) in 5 minutes.
- If greater than the specified range, replace the fuel pump.
- Remove the J 37287 and J 34730-1A . 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.