Fuel Delivery and Air Induction: Description and Operation

The fuel supply system consists of a fuel tank, in-tank high pressure fuel pump, main relay, fuel filter, pressure regulator, injectors and injector resistor. This system delivers pressure regulated fuel to the injectors and cuts fuel delivery when the engine is not running.

FUEL INJECTORS
The injectors are a solenoid activated, constant-stroke pintle type consisting of a solenoid, plunger needle valve and housing. When current is applied to the solenoid coil, the vale lifts up and pressurized fuel is injected. Since the needle valve lift and fuel pressure are constant, the injection quantity is determined by the length of time that the valve is open. The injector is sealed by an 0-ring and seal ring at the top and bottom.

INJECTOR RESISTOR
The resistor lowers the current supplied to the injectors to prevent damage to the injector coils. This allows a faster response time of the injectors.

PRESSURE REGULATOR
The fuel pressure regulator maintains a constant fuel pressure to the injectors. When the difference between the fuel pressure and manifold pressure exceeds 43 PSI (3.0 kg / cm2), the diaphragm is pushed upward, and the excess fuel is fed back into the fuel tank through the return line.

FUEL PUMP
The fuel pump is comprised of a DC motor, a circumference flow pump, a relief valve for protecting the fuel line systems, a check valve for retaining residual pressure, an inlet port, and a discharge port. The pump assembly consists of the impeller (driven by the motor), the pump casing (which forms the pumping chamber), and the pump cover.

MAIN RELAY
The main relay contains two individual relays. This relay is installed at the left side of passenger compartment behind the dash. One relay is energized whenever the ignition is on, and supplies battery voltage to the ECM, injectors and to the second relay. The second relay is energized for 2 seconds when the ignition is switched on, and supplies power to the fuel pump when the engine is running.

FUEL TANK
The fuel tank contains the fuel pump, fuel gauge sending unit, two-way valve, and fuel filler neck. The fuel tank is sealed from from outside influences, fuel vapors are routed through hoses to the charcoal canister. When fuel vapors expand in the fuel tank, the two-way valve, relieves internal pressures and sends the vapors to the charcoal canister.