How to Replace a GMC Truck Fuel Pump
The fuel pumps on GMC’s are actually in the fuel tanks unfortunately. Thus it is necessary to remove the fuel tank to replace the pump. Generally you can plan on replacing the pump and while you are at it you should replace the sensor unit as well.
Items you will require:
- Floor jack or wheel ramps
- Wrench
- Locking pliers
- Screwdrivers
- Hammer with a brass punch
- Shop towels
- Start by disconnecting the cable from your truck’s negative post.
- Remove the fuel cap. Use shop towels around the opening and with a small screwdriver relieve the fuel pressure by pressing the valve in the port with a screwdriver.
- Jack up the truck or pull it back on the wheel ramps. Block the front tires so it cannot move forward.
- Use your wrench and remove the fuel tanks rock guard. Loosen the hose clamp to the filler neck and vent hose and remove them. Disconnect the EVAP canister and then the fuel supply line at its quick-connect fitting.
- Take the wrench and remove the bolts holding the gas tank. Disconnect the fuel pump connections and remove the tank.
- Use the locking pliers and remove the retaining ring by turning it counterclockwise to unscrew it and remove it. Should it need a “tap” to get it loose use the hammer with your brass punch (do not use steel as it could spark!).
- Lift out the fuel pump and disconnect the ventilation harness with the quick disconnect fitting on the harness.
- Check the “O” ring around the mounting hole to make certain it is still in good condition. If it is not replace it.
- Reconnect the ventilation quick connect fitting and lower the new pump into the fuel tank. Be careful not to damage the float arm.
- Use the locking pliers and screw down the locking ring again. Reconnect the fuel supply and vent lines and the electrical connectors to the mounting flange using the quick connect fittings.
- Place the fuel tank back where it belongs and secure with the straps and bolt them into place with the wrench.
- Reconnect the filler and vent hoses and any other supply and EVAP lines.
- Place the rock guard and remove the chocks from the front of the truck. Drive forward off the wheel ramps after replacing the negative battery cable.