Diesel Fuel Injection: Description

The Mazda diesel pickup fuel injection system consists of a combination injection pump and fuel distributor, 4 fuel injection nozzles, a fuel filter with an integral priming pump, a water separator, fuel lines and the fuel tank. The injection system is also tied in with a quick start (glow plug) system.

The injection pump is a vane type pump and is driven by the engine timing gears. An altitude compensator and a cold start device are installed on the pump to modify injection duration as necessary. The distributor portion of the pump contains a fuel cut solenoid to stop fuel flow to the injectors after the ignition switch is turned off. See Figure.

The injectors use a needle type valve at the end of the nozzle. Injector opening pressure can be changed by adding or subtracting adjusting shim thickness. The adjusting shim is located just above the needle valve return spring in the injector.

The quick start system consists of a glow plug in each cylinder, 2 relays, a ballast resistor, a glow plug control unit as well as various switches and warning lights.