Mechanical fuel pumps are attached directly to the engine and a lever on the pump is operated by an eccentric on the camshaft, which pulls down the flexible diaphragm to draw fuel into the pump by creating a vacuum. The pump chamber volume is decreased or increased by flexing the diaphragm. Diaphragm spring pulls the diaphragm up, the force enables fuel to be expelled from the pump. The parts of mechanical fuel pumps are :
1. Upper body
2. Lower body
3. Valve plate
4. Diaphragm
5. Return spring
6. Pushrod
7. Rocker arm
1. Upper body
2. Lower body
3. Valve plate
4. Diaphragm
5. Return spring
6. Pushrod
7. Rocker arm