2000 GMC Sonoma Install a Fuel Pump
The fuel injection system on the 2000 GMC Sonoma is pressurized by the fuel pump. The pump pulls fuel from the tank, delivers it through the fuel filter and provides pressurized fuel to the engine's injectors. When the fuel pump begins to wear out, fuel delivery to the engine suffers. A worn or failing fuel pump requires removal from the Sonoma fuel tank for either rebuild or complete replacement.
 Tools Used
|3/4-inch combination wrench|
|7/8-inch combination wrench|
 Install a Fuel Pump
- Remove the bed of the truck to gain access to the Sonoma's fuel pump. The pump flush mounts to the top of the truck's fuel tank. With the bed removed, the pump is available for service or replacement.
- Unplug the tail light and license plate wiring harness. With the wiring harness connectors disconnected, remove the plastic harness supports along the bottom edge of the truck bed to prevent pulling them out when the truck box is taken off.
- Unscrew the hose clamp securing the fuel tank fill-up line to the fill spout on the truck bed. A standard flathead screwdriver will fit the clamp and provide a means to gently pry the fill line loose from the spout.
- Unbolt the truck box by removing the carriage-bolt nuts from underneath the bed. The nuts are manageable with a 3/4-inch or 7/8-inch combination wrench. With all carriage bolts out of the way, get some help from a second person, and lift the bed from the truck.
- Disconnect the fuel evaporative lines connected to the fuel sending unit on top of the fuel tank. With the lines removed, unplug the electrical connector, and move it out of the way.
- Remove the snap-ring securing the fuel sending module into the gas tank. Use a standard pair of snap-ring pliers to take the ring out of its groove. Keep a second hand over the top of the snap ring to prevent it from flying out and getting lost.
- Pull the fuel sending unit assembly up and out of the tank, and set it out of the way. Remove the old o-ring from the hole left by the sending unit.
- Lightly coat the new o-ring with petroleum jelly, and insert it into the o-ring groove around the fuel sending unit port on the tank.
- Set the new unit into the tank, using care not to pinch or reposition the o-ring. Push the assembly flush with the top of the tank until the snap-ring groove is visible.
- Install the snap ring to secure the new fuel sending unit into the tank. Ensure the unit is oriented in the same manner as the old unit before removal.
- Connect the electrical connector to the sending unit, followed by the fuel evaporative lines. The lines simply press onto the hose barbs protruding from the top of the sending unit.
- Set the truck box onto the truck frame. Install the carriage bolts and wiring harnesses for the tail and license plate lights.
- Set the fuel fill-up line into place on the fuel spout, and secure it into place with the fuel line clamp.
 Tips & Warnings
- Remove the fuel from the fuel tank before attempting to service the fuel pump.
- Disconnect the negative and positive battery terminals before working with the vehicle's electrical system.