4.10
9929422 R02 - 2017-2019 ACE 900 Service Manual
© Copyright Polaris Industries Inc.
FUEL INJECTOR
FUEL INJECTOR OVERVIEW
The fuel injectors
q
are mounted into the intake plenum,
with the fuel rail retaining them from the top end. O-rings
on both ends of the injector prevent external fuel leaks
and also insulate the injectors from heat and vibration.
When the key switch is on, the fuel rail is pressurized,
and the EFI relay provides voltage to the injectors.
During engine operation, the ECU completes the ground
circuit, energizing the injectors. The valve needle in each
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 contains a series
of calibrated openings which directs the fuel into the
intake port in a cone-shaped spray pattern.
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 may vary in length depending on the speed and
load requirements of the engine.
The ECU gathers fuel injection timing information from
the Crankshaft Position Sensor (CPS) and the Pedal
Position Sensor (PPS) to allow for sequential fuel
injection.
FUEL INJECTOR O-RINGS
1. Any time an injector is removed, you must replace the
upper and lower O-rings.
2. Always lubricate NEW injector o-rings with clean,
silicone-free motor oil.
NOTICE
Apply oil sparingly and avoid contaminating the pintle
valve / jet surface and upper inlet port.
3. Install NEW o-rings onto top and bottom of injector
ITEM PART
NUMBER
COLOR POSITION
q
1500198 Blue
TOP OF
INJECTOR
w
5415066 Brown
BOTTOM OF
INJECTOR
IMPORTANT
Always install NEW o-rings when removing the fuel rail
or injectors.
IMPORTANT
Verify that the new top and bottom o-rings are installed
in the correct position and are lubricated with clean,
silicone-free oil.
FUEL SYSTEM
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