Fuel Control
An electric, positive displacement, roller vane type fuel pump is located in the fuel tank. The fuel pump contains 2 check valves. One check valve, located near pump outlet, restricts fuel movement in either direction when pump is not running. The other check valve relieves internal pump pressure and regulates maximum pump output.
The fuel pump is an integral part of the fuel sending unit. A fuel pressure regulator mounted downstream of fuel injectors, on the fuel rail, maintains fuel pressure at a constant 48 psi (3.4 kg/cm2 ). The canister purge solenoid also controls fuel pressure. See EMISSION CONTROL in this article for more information.
Power to the fuel pump is supplied by the SMEC through the Automatic Shutdown (ASD) relay. The SMEC receives an ignition signal from the distributor. When the SMEC does not receive this signal with ignition switch in "RUN" position, power is shut off to the fuel pump, fuel injectors and ignition coil through the ASD relay.
The electrically controlled fuel injectors are controlled by the SMEC. The SMEC determines when to energize injectors and pulse width of injectors. When electrical current is supplied to an injector, the armature and pintle move a short distance against a spring, opening a small orifice. Fuel pressure forces fuel through this opening, resulting in a fine spray in the shape of a hollow cone.