The fuel system consists of the following components:

The fuel tanks store the fuel supply. An electric fuel pump, located in the fuel tank with the fuel sender assembly, pumps fuel through an in-line fuel filter to the TBI unit. The pump is designed to provide fuel at a pressure greater than is needed by the injectors. The pressure regulator, part of the TBI assembly, keeps the fuel available to the injectors at a regulated pressure. A separate line returns the unused fuel to the fuel tank.

The fuel tanks, mounted on the frame rails, are held in place by two metal straps.

In order to help prevent refueling with leaded gasoline, the fuel filler neck on a gasoline engine vehicle 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, will result in gasoline splashing back out of the filler neck.

The fuel tank filler neck is equipped with a screw-type cap. The threaded part of the cap requires several turns counterclockwise in order to remove. The long threaded area was designed in order to allow any remaining fuel tank pressure to escape, while the cap was being removed.

The fuel sender assembly is located inside the fuel tank and is attached to the top of the fuel tank.

The fuel sender assembly consists of the following major components:

The fuel pump is a turbine type, medium pressure, electric pump, mounted in the fuel tank. The fuel pump pumps the fuel at a specified flow and pressure through the in-line filter to the pressure regulator in the TBI unit. Excess fuel returns to the fuel tank through the fuel return line.

The fuel pump is attached to the fuel sender assembly. A fuel strainer is attached to the fuel pump inlet line and prevents the dirt particles from entering the fuel line and tends to separate the water from the fuel.

A woven plastic fuel pump strainer is attached to the lower end of the fuel pump in the fuel tank. The functions of the fuel pump strainer are to filter contaminants and to wick the fuel.

The life of the fuel pump strainer is generally considered to be that of the fuel pump. The fuel pump strainer is self-cleaning and normally requires no maintenance. Fuel stoppage at this point indicates that the fuel tank contains an abnormal amount of sediment or water, in which case, thoroughly clean the tank. Refer to Fuel Tank Purge Procedure and Fuel System Cleaning . If the fuel pump strainer is plugged, replace it with a new fuel pump strainer.

A steel in-line fuel filter is used in the fuel feed pipe ahead of the fuel injection system. The filter element, made of paper, traps particles in the fuel that may damage the injection system. The filter housing is constructed to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature.

Caution: In order to reduce the risk of fire and personal injury observe the following items:

Nylon fuel pipes are designed to perform the same job as the steel or rubber fuel tubes they replace. Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to fuel additives, and changes in temperature. There are two sizes used: 3/8 inches ID for the fuel feed, and 5/16 inches ID for the fuel return.

The fuel feed and return pipes are assembled as a harness. Retaining clips hold the pipes together and provide a means for attaching the pipes to the vehicle. Quick-connect type fittings are used at the ends of the fuel feed/return pipes and at the in-line fuel filter. Sections of the pipes that are exposed to chafing, high temperature, or vibration are protected with heat resistant rubber hose and/or corrugated plastic conduit.

Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle. However, if forced into sharp bends, nylon pipes will kink and restrict the fuel flow. Also, once exposed to fuel, nylon pipes may become stiffer and are more likely to kink if bent too far. Some special care should be taken when working on a vehicle with nylon fuel pipes.

Quick-connect type fittings provide a simplified means of installing and connecting the fuel system components. There are two types of quick connect fittings, each used at different locations in the fuel system. Each type consists of a unique female socket and a compatible male connector. O-rings, located inside the female socket, provide the fuel seal. Integral locking tabs or fingers hold the fittings together. The metal collar quick-connect fittings used at the braided steel pipes have locking tabs that require a special tool to release. The plastic collar quick-connect fittings used at the other connections have hand releasable locking tabs.

Caution: In order to reduce the risk of fire and personal injury observe the following items:

The vapor pipe extends from the fuel sender assembly to the charcoal canister. It is made up of nylon pipe and is connected to the fuel sender assembly and the charcoal canister with fuel resistant rubber hoses.

Fuel feed and return pipe threaded connections at the TBI unit are sealed with replaceable O-ring seals. These O-ring seals are made of special material. Service with the correct service part.

When the key is first turned ON without the engine running, the ECM turns a fuel pump relay ON for 2 seconds. This builds up the fuel pressure quickly. If the engine is not started within two seconds, the ECM shuts the fuel pump OFF and waits until the engine starts. As soon as the engine is cranked, the ECM turns the relay ON and runs the fuel pump.

When the engine cranks or runs, the ECM receives the distributor reference pulses which in turn energizes the fuel injectors.

As a backup system to the fuel pump relay, the fuel pump can also be turned ON by an oil pressure switch. When the engine oil pressure reaches about 28 kPa (4 psi), through cranking and the fuel pump relay does not complete the circuit, the oil pressure switch will close to complete the circuit to run the fuel pump.

An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold. The oil pressure switch will turn ON the fuel pump as soon as oil pressure reaches about 28 kPa (4 psi).