II. Engine Component Description
U L-Series Diesel 5
Pump Description
All L-series engines use individual injection pumps
to supply fuel to the injection nozzles. The fuel
pumps are mounted to the engine block, and are
operated by the camshaft. Inside of the pump, there
is a plunger barrel, timing sleeve, and plunger
assembly. The plunger barrel contains the pump’s
timing sleeve. The barrel uses a guide pin to locate
the timing sleeve in the correct position. The
internal area of the plunger barrel also serves as the
fuel reservoir. The timing sleeve fits over the
plunger and both components fit inside of the
plunger barrel
The timing sleeve component contains both the
fill port and the spill port. Fuel enters the
pressure chamber through the fill port. As the
plunger rises, it closes the fill and spill ports,
forcing pressurized fuel out the delivery valve to
the injector nozzle. Any residual fuel is bled off
through the spill port on the plunger return
stroke.
Pump timing is determined by the thickness of
shims placed between the pump housing and the
cylinder block. Each shim varies in thickness by
.1mm (.004”), creating a 1
change in timing
(thicker=retard, thinner=advance). The shims are
a “crush” design and must not be reused.
IMPORTANT: All pump shims must be of
the same thickness when replaced. No single
pump can have a different thickness shim
If this cannot be achieved, there could
be a problem with the injection pump. During
the warranty period, a pump requiring service
be returned to an authorized Zexel
distributor.
Timing SleevePlunger
Barrel
Pin
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