GM Repair Questions? Ask a Mechanic for Answers ASAP
The fuel supply system consists of the following components:
The fuel supply system has an electric fuel pump located in the fuel tank on the gauge sending unit. The electric pump pumps fuel to the fuel injection unit through an in-line fuel filter and fuel supply line. The pump provides fuel at a pressure above the regulated pressure needed by the fuel injectors.
A pressure regulator in the fuel injector unit keeps fuel available to the injector at a constant pressure. Fuel in excess of injector needs is returned to the fuel tank by a separate line.
Fuel pressure for Central SFI 4.3L system is 380-420 kPa (55-61 psi).
In order to properly control the fuel supply, the fuel pump is operated by the control module through the fuel pump relay and oil pressure switch. In-Line Fuel Filter
Caution: In order to reduce the risk of fire and pesonal injury, allow the fuel pressure to bleed off before servicing the fuel system components.
The in-line filter is located in the fuel feed line. This filter prevents dirt from entering the injection unit.
A woven plastic filter is located on the lower end of the fuel pickup tube in the fuel tank. The filter prevents any dirt from entering the fuel line. Unless the filter becomes completely submerged, the filter also stops water.
This filter is self-cleaning. The filter normally requires no maintenance. At this point, the fuel stoppage indicates that the fuel tank contains an abnormal amount of sediment or water; therefore, clean the tank thoroughly.
The fuel feed and the return pipes and the hoses extend from the fuel pump and the sender to the injection unit. The fuel feed and the return pipes and the hoses are routed along the frame side member.
The vapor pipe and the hoses extend from the fuel pump and the sender unit to the Evaporative Emission (EVAP) control vapor canister.
The fuel tank, at the rear of the underbody, is held in place by 2 metal straps. Anti-squeak pieces are used on top of the tank to reduce rattles.
In order to help prevent refueling with leaded gasoline, the fuel filler neck on a gasoline engine vehicles has a built-in restrictor and deflector. The opening in the restrictor will only admit the smaller unleaded gas nozzle spout, which must be fully inserted to bypass the deflector.
Attempted refueling with a leaded gas nozzle or failure to fully insert the unleaded gas nozzle results in gasoline splashing back out of the filler neck.
The fuel tank filler neck is equipped with a tethered fuel tank filler cap. Turn the cap counterclockwise in order to remove. A built-in torque-limiting device prevents overtightening. In order to install the cap, turn the cap clockwise until a clicking noise is heard. The clicking is a signal to the operator that the correct torque has been reached and the cap is fully seated.
The accelerator control system is a control cable type attached at one end to an accelerator pedal assembly. On the other end is the throttle valve.