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Diesel fuel
contains varying degrees of entrained air in the
form of foam on the surface or suspended in the
bulk fluid as tiny bubbles. Additionally, fuel
is driven into the fuel pump by atmospheric
pressure, which is usually only enough pressure
flow to fill the pump at idle speeds.
Consequently, at higher operating RPM’s, the
stock pump cavitates producing vapor.
Air and vapor are
compressible. The presence of air/vapor in the
fuel injector delays the pressure build-up.
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This delays the
injection, resulting in Retarded Injection
Timing.
Retarded injection
timing in a diesel, just like bad spark plugs in
a gasoline engine, causes lost power, poor fuel
mileage, and an increase in exhaust emissions.
Retarded Injection Timing caused by air/vapor is
the primary source of the rough idle, lost
power, increased fuel consumption and excessive
exhaust emissions of the diesel engine. |
Air/vapor in the
injector can also cause permanent
damage in the
form of galling and pitting of the
barrel/plunger
assembly and tip erosion.
The conventional
vacuum feed fuel
supply system
does nothing
to remove entrained air from the fuel.
In fact, it only makes things
worse. As the filter plugs with use,
the already inadequate
fuel flow to the engine is further
reduced, increasing
cavitation and retarding injection
timing even more. |
