The GMC Jimmy utilizes an electrical fuel pump mounted inside the fuel tank to move gasoline from the fuel tank to the engine. Symptoms of a faulty fuel pump include hard starting, engine stalling and stumbling during acceleration. When servicing the fuel system on any vehicle you must remember that gasoline is highly volatile; take special precautions while working with it. Always work in a well-ventilated area, and be aware of any sources of heat or spark.
Instructions
Relieving the Fuel Pressure
1. Park your Jimmy on a level surface. Set the parking brake, and block the rear tires with the wheel chocks.
2. Remove the fuel filler cap to release pressure inside the fuel tank.
3. Remove the fuel pump fuse from the fuse block on early-model vehicles. On newer vehicles, disconnect the three terminal plastic electrical connectors at the fuel tank.
4. Start the engine, and allow it to run until it stalls. Then start the engine and allow it to turn over for three to five seconds, so that all the pressure is drawn out of the fuel lines.
5. Open the hood. Disconnect the ground cable from the negative battery terminal by loosening the retaining bolt, using a wrench, and pulling the clamp off the negative terminal.
6. Reinstall the fuel pump fuse, or reconnect the plastic wiring connector at the fuel tank.
Removing the Fuel Tank
7. Drain the fuel tank using a battery-powered or hand-operated fuel siphon.
8. Raise the rear of the Jimmy with the jack, and support the vehicle with jack stands placed underneath the rear axle.
9. Loosen the retaining clamp with a Phillips screwdriver, and remove the fuel filler neck from the tank.
10. Label and disconnect any accessible hoses and wiring connected to the top of the tank, using masking tape and a marker.
11. Remove the fuel tank straps. Have an assistant support the tank while you use an appropriate-size socket to remove the bolts that connect the fuel tank straps to the vehicle's body.
12. Lower the tank slightly; then label and remove any remaining fuel or electrical connections at the top of the tank.
13. Remove the fuel tank from the vehicle.
Removing and Installing the Fuel Pump in the Fuel Tank
14. Use GM fuel gauge sending unit retaining cam tool No. J-24187, or a brass drift and hammer, to remove the cam locking ring from the fuel tank by rotating it counterclockwise.
15. Carefully lift the fuel tank sending unit and pump from the fuel tank.
16. Remove the fuel pump from the sending unit: Slide it upward onto the mounting tube, then slide the bottom of the pump away from the bottom support. Slide the pump down to disengage it from the mounting tube.
17.Remove and discard the rubber O-ring seal between the sending unit and the fuel tank.
18. Slide the new fuel pump onto the mounting tube. Make sure the bottom of the pump is seated on the bottom support.
19. Install a new rubber O-ring seal on the sending unit mounting surface on the tank.
20. Lower the fuel pump and sending unit into the fuel tank. Exercise care when doing this.
21. Using the retaining cam tool, reinstall the cam locking ring onto the fuel tank by turning it clockwise.
Reinstalling the Fuel Tank
22. Lift the tank into position with the help of an assistant.
23. Reinstall the rearmost tank retaining strap by lifting the tank strap into position and reinstalling the bolts that connect them to the vehicle's body.
24. Reconnect the fuel filler neck by sliding the neck over the inlet tube on the tank and tightening the retaining clamp.
25. Reconnect the electrical wires and fuel lines to the top of the tank, following the labels you made during disassembly.
26
Reinstall the front fuel tank retaining straps by lifting each strap into position and reinstalling the bolts that connect it to the vehicle's body.
Testing
27
Lower the rear of the vehicle.
28
Fill the fuel tank with gasoline.
29
Reconnect the ground cable to the negative battery terminal by sliding the clamp over the negative battery terminal and tightening the retaining bolt.
30
Run the engine, and visually inspect for leaks around the tank.
Tips Warnings
Drive the vehicle until the fuel tank is nearly empty, if possible, before beginning this procedure.
Gasoline is highly flammable. Do not smoke or allow others around you to smoke while servicing the fuel system.
Always follow the instructions listed in the owner's manual when lifting or lowering a vehicle. Failure to do so could cause injury or death.
Do not attempt to drain the fuel using your mouth.
Tags: install, fuel, pump, jimmy, fuel tank, sending unit, fuel pump, fuel tank, fuel tank, Remove fuel, battery terminal, bolts that, bolts that connect
