
152 LIGHT AND HEAVY VEHICLE TECHNOLOGY
Tightening screw Filter head
- Filler plug
Spiral V form
element
Felt tube
filter element
(coarse)
Figure 8.6 Two-stage fuel oil filter incorporating a cross-
flow coarse element
The plunger type of lift pump comprises a spring-
energized piston that reciprocates in a pumping chamber
containing the inlet and outlet valves (Figure 8.8). A
diaphragm is arranged in series with the pumping piston,
its purpose being to seal against any fuel oil that leaks
past the piston. In a more recent version with improved
sealing, a second diaphragm has been introduced for
retaining oil in the fuel injection pump cambox