Fuel Pump: Description and Operation

Fuel System:

DESCRIPTION
This diesel engine uses a mechanical fuel pump located on the front right side of the engine. The pump is a diaphragm type pump and is actuated by a rocker arm through a link and pull rod.

OPERATION
The fuel pump rocker arm is moved back and forth by a rod which rides on an eccentric on the engine camshaft. The rocker arm pulls down on the pump diaphragm against spring pressure. This causes a vacuum in the pump chamber which draws fuel from the tank through the inlet valve. The camshaft rotates and releases pressure on the arm. This allows the spring to act on the diaphragm and force fuel out of the pump chamber through the outlet valve and into the fuel line diesel fuel injection pump.

When the immediate fuel needs of the diesel engine are satisfied, pressure builds in the fuel line and pump chamber. This pressure forces the diaphragm/piston to make shorter and shorter strokes, until more fuel is needed in the engine.