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ELECTRONIC FUEL INJECTION
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9924096 - 2013 RANGER RZR XP 900 / RZR XP 4 900 Service Manual
© Copyright 2012 Polaris Sales Inc.
ELECTRONIC FUEL INJECTION
Principal Components
The Electronic Fuel Injection (EFI) system is a complete
engine fuel and ignition management design. This system
includes the following principal components:
• Check Engine Light
• Crankshaft Position Sensor (CPS)
• Dual Throttle Body / lntake Adapter
• Engine Control Unit (ECU)
• Engine Coolant Temperature Sensor (ECT)
• Fuel Filter(s)
• Fuel Injectors
• Fuel Pressure Regulators
•Fuel Pump
• Fuel Rail
• Fuel Supply/Return Lines
• Idle Air Control Valve (IAC)
• Ignition Coil
• Manifold Air Quality Sensor (MAQS)
• Wire Harness Assembly
EFI Operation Overview
The EFI system is designed to provide peak engine
performance with optimum fuel efficiency and lowest
possible emissions. The ignition and injection functions
are electronically controlled, monitored and continually
corrected during operation to maintain peak performance.
The central component of the system is the Bosch M17
Electronic Control Unit (ECU) which manages system
operation, determining the best combination of fuel
mixture and ignition timing for the current operating
conditions.
An electric fuel pump is used to move fuel from the tank,
through the fuel supply line, to the fuel rail. Fuel pressure
regulators located in the tank and on the end of the fuel rail,
maintain system operating pressure and return excess
fuel back into the fuel tank. At the engine, fuel fed through
the fuel rail supplies fuel to the injectors, which inject into
the intake ports. The ECU controls the amount of fuel by
varying the length of time that the injectors are "on." This
range can vary depending on fuel requirements. The
controlled injection of the fuel occurs every other
crankshaft revolution, or once for each 4-stroke cycle.
When the intake valve opens, the fuel/air mixture is drawn
into the combustion chamber, ignited and burned.
The ECU controls the amount of fuel being injected and
the ignition timing by monitoring the primary sensor
signals for intake air temperature, manifold absolute
pressure (load), engine temperature, engine speed (RPM)
and throttle position. These primary signals are compared
to the programming in the ECU computer chip, and the
ECU adjusts the fuel delivery and ignition timing based on
these values.
During operation, the ECU has the ability to re-adjust
temporarily; providing compensation for changes in
overall engine condition and operating environment, so it
will be able to maintain the ideal air/fuel ratio.
During certain operating periods such as cold starts, warm
up, acceleration, etc., a richer air / fuel ratio is
automatically calculated by the ECU.
Initial Priming / Starting Procedure
NOTE: The injection system must be purged of all
air prior to the initial start up, and / or any time the
system has been disassembled.
If the EFI system is completely empty of fuel or has been
disassembled and repaired:
1. Cycle the key switch from “OFF” to “ON” 6 times,
waiting for approximately 3 seconds at each “ON”
cycle to allow the fuel pump to cycle and shut down.
2. Once step 1 is completed, turn the key switch to
“START” until the engine starts or 5 seconds has
passed.
3. If the engine failed to start, repeat step 1 for 2 more
cycles and attempt to start the engine.
If the engine fails to start, a problem may still exist, and
should be diagnosed.
NOTE: Accurate testing of EFI components is
recommended utilizing the Digital Wrench®
Diagnostic Software (dealer only).
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