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FUEL SYSTEM / FUEL INJECTION
4.12
FUEL PRESSURE REGULATOR TEST
Refer to the Fuel Pump Test procedure.
FUEL PRESSURE REGULATOR
REPLACEMENT
The regulator is a sealed, non--serviceable assembly.
If it is faulty, the pump assembly must be replaced.
Refer to the Fuel Pump/Tank Assembly Replacement
procedure.
FUEL FILTERS
NOTE: 800 EFI fuel connections are quick--connect
couplings vs 700 EFI connections.
EFI Engines use a non--serviceable, high--volume,
high--pressure, 30--micron internal fuel pump filter
and a replaceable 10--micron, in--line fuel filter.
700 EFI Shown
FUEL FILTER SERVICE
In line filter replacement is recommended every 2
years of operation or more frequently under extremely
dusty, dirty conditions. Use only the specified filter,
and install it according to the directional arrows. DO
NOT use an aftermarket filter, as operating
performance and safety can be affected.
FUEL FILTER REPLACEMENT
To replace the filter:
1. Relievesystem pressure through the test valve in
the fuel rail before servicing.
2. Loosen clamps and slide hose off the filter ends.
3. Install new filter with arrow pointing to the fuel line
connected to the injector rail.
NOTE: When replacing the fuel filter, wet the interior
of the new filter with gasoline before installation to
ensure high pump pressure doesn’t tear the filtering
material.
FUEL INJECTORS
NOTE: 800 EFI fuel connections are quick--connect
couplings vs 700 EFI connections.
The fuel injectors mount into the intake manifold, and
the fuel rail attaches to them at the top end.
Replaceable O--Rings on both ends of the injector
prevent external fuel leakage and also insulate it from
heat and vibration.
Injector
When the key switch is on, the fuel rail is pressurized,
and voltage is present at the injector. At the proper
instant, the ECU completes the ground circuit,
energizing the injector. The valve needle in the
injector is opened electromagnetically, and the
pressure in the fuel rail forces fuel down through the
inside. The ”director plate” at the tip of the injector (see
inset) contains a series of calibrated openings which
directs the fuel into the intake port in a cone--shaped
spray pattern.
The injector is opened and closed once for each
crankshaft revolution, however only one--half the total
amount of fuel needed for one firing is injected during
each opening. The amount of fuel injected is
controlled by the ECU and determined by the length
of time the valve needle is held open, also referred to
as the .’injection duration” or”pulse width”. It mayvary
in length from 1.5--8 milliseconds depending on the
speed and load requirements of the engine.