Engine Performance and Fuel Range Conditions
March 29, 2019
A lack of engine performance along with an incorrect low fuel range display may be found on some
2017-2018 Acadia, Enclave, Traverse and XT5 models equipped with the 3.6L V6 engine (RPOs LFY, LGX) and all-wheel-drive (AWD).
The following DTCs also may be set in the Engine Control Module (ECM):
- P018B: Fuel Pressure Sensor Performance
- P2635: Fuel Pump Flow Performance
- P0461: Fuel Level Sensor 1 Performance
- P0462: Fuel Level Sensor 1 Circuit Low Voltage
- P0463: Fuel Level Sensor 1 Circuit High Voltage
- P0464: Fuel Level Sensor 1 Circuit Intermittent
- P2066: Fuel Level Sensor 2 Performance
- P2067: Fuel Level Sensor 2 Circuit Low Voltage
- P2068: Fuel Level Sensor 2 Circuit High Voltage
These conditions may be caused by a partially or completely blocked port on the primary in-tank fuel pump module transfer jet manifold. The blockage of the port inhibits the suction to the fuel transfer line, which leads to an inability to transfer fuel from the secondary side on fuel tanks of AWD models.
AWD models have a fuel tank with a saddle configuration in order to provide space for the driveshaft through the center area of the fuel tank. Because of the saddle shape of the tank, two fuel tank fuel pump modules are required. (Fig. 15) Fuel is drawn from the secondary side of the fuel tank, through the fuel transfer pipe, to the primary side of the fuel tank.
To diagnose this condition, check fuel lever sensor resistance for both fuel level sensors at the x350 connector (Chassis Harness to Fuel Tank Harness). (Fig. 16) If the primary and secondary sensors are both at 250 ohms, it indicates that the entire tank is empty and the transfer of fuel is occurring. Check the operation of the fuel gauge. However, if the primary sensor is at 250 ohms, but the secondary sensor is less than 250 ohms, it indicates that the primary side is empty, yet the secondary side has fuel.
Using care, lower the fuel tank, leaving any remaining fuel on the secondary side. Verify the transfer hose is connected to the secondary sender base and the fuel level sensor moves freely. Also check the function of the primary fuel level sender verify that it sweeps freely with no interference. Both fuel level sensor readings sweep from 40-250 ohms.
If there is fuel on the secondary side and there are no other concerns, replace the primary fuel pump module. If the primary fuel pump module is found to be the cause, only replace the pump module and not the fuel level sensor.
Next, confirm fuel level sensor resistance for both fuel level sensors at the x350 connector and compare to the initial readings.
Install the fuel tank (with the fuel on the secondary side) and add a gallon of fuel, which will go to primary side. Start the engine and allow time for the primary fuel pump module transfer jet to pull the fuel from the secondary side.
Measure the x350 connector fuel level sensor resistances and verify that the secondary fuel level sensor resistance goes toward approximately 250 ohms and the primary fuel level sensor resistance goes down from 250 ohms toward 40 ohms.
Refer to Bulletin #18-NA-365 for additional information.