GM 19369904 MODULE KIT,F/TNK F/PMP

To check the fuel level sending unit, start by removing it and using an ohmmeter to measure the resistance as the float moves from empty to full. Look for a smooth change in resistance. If there is no resistance or very little change, the sending unit needs to be replaced. To remove the sending unit, first relieve the fuel pressure and disconnect the battery cable. Then, remove the fuel tank and the necessary components in the trunk. Disconnect the electrical connectors and quick-connect fittings for the fuel tank pressure sensor and fuel pump/fuel level sending unit. Use a brass punch or water pump pliers to turn the lock ring counterclockwise and remove the fuel pump/fuel level sending unit module from the tank. Inspect the condition of the o-ring and replace if necessary. If replacing the sending unit, separate it from the fuel pump assembly. Installation is the reverse of removal.

To check the fuel pump output and pressure, first ensure that there is enough fuel in the tank and relieve the fuel pressure. Then, install a fuel pressure gauge onto the fuel lines or fuel rail using the appropriate adapter fitting. With the ignition switch on but the engine not running, observe the fuel pump running for about two seconds and note the reading on the gauge. After the pump stops running, the pressure should remain steady within the specified range. If the pump does not turn on, check the fuel pump's electrical circuits. Start the engine and let it idle at normal operating temperature, and the pressure should be slightly lower. If all pressure readings are within specifications, the system is functioning properly. If the pressure did not drop after starting the engine, apply vacuum to the pressure regulator. If the pressure drops, repair the vacuum source; if not, replace the regulator. If the fuel pressure is not within specifications, check for vacuum to the pressure regulator and for a pinched or clogged fuel return hose or line. If these are okay, replace the pressure regulator. If the pressure is still low with the fuel return line restricted, the fuel pump may be faulty. After testing, relieve the fuel pressure and remove the gauge. For the fuel pump electrical circuit check, listen for a whirring sound at the fuel filler neck opening when the ignition key is turned on. If no sound is heard, check the fuel pump fuse. If the fuse is okay, remove the fuel pump relay and check for battery voltage to the relay connector with the ignition key off and on. If there is no voltage, check the fuel pump fuse and wiring circuit. If voltage is present, check the relay and then check for battery voltage at the fuel pump connector. If there is no voltage, check for an open circuit between the fuel pump and the relay. If there is power at the fuel pump connector and the pump still does not work, try bypassing the fuel pump circuit and powering it up with battery voltage. Additionally, check the oil pressure and oil pressure switch if the fuel pump fails to operate.

To remove the fuel pump/fuel level sending unit from the fuel tank, start by disconnecting the fuel level sending unit electrical connector from the module cover. Then, remove the sending unit retaining clip and pinch the tabs together to slide the fuel level sending unit off the module, taking note of the wiring routing for installation. Reassembly is simply the reverse of disassembly. Finally, install the fuel pump/fuel level sending unit back into the fuel tank.

To check the fuel level sending unit, start by removing it and using an ohmmeter to measure the resistance as the float moves from empty to full. Look for a smooth change in resistance. If there is no resistance or very little change, the sending unit needs to be replaced. To remove the sending unit, first relieve the fuel pressure and disconnect the battery cable. Then, remove the fuel tank and the necessary components in the trunk. Disconnect the electrical connectors and quick-connect fittings for the fuel tank pressure sensor and fuel pump/fuel level sending unit. Use a brass punch or water pump pliers to turn the lock ring counterclockwise and remove the fuel pump/fuel level sending unit module from the tank. Inspect the condition of the o-ring and replace if necessary. If replacing the sending unit, separate it from the fuel pump assembly. Installation is the reverse of removal.

Start by disconnecting the fuel level sending unit electrical connector from the module cover.

If all pressure readings are within specifications, the system is functioning properly.