Polaris 2012 Sportsman Forest 500 International, Service Manual

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4.37
500 EFI FUEL SYSTEM
4
9923412 - 2012 Sportsman 400/500 and EFI Tractor Service Manual
© Copyright 2011 Polaris Sales Inc.
ELECTRONIC FUEL INJECTION
General Information
The Electronic Fuel Injection (EFI) system is a complete
engine fuel and ignition management design. This system
contains the following principal components:
• Fuel Pump
• Fuel Rail
• Fuel Line(s)
• Fuel Filter(s)
• Fuel Injector
• Pressure Regulator
• Throttle Body / lntake Manifold
• Engine Control Unit (ECU)
• Ignition Coils
• Engine Coolant Temperature Sensor (ECT)
• Throttle Position Sensor (TPS)
• Crankshaft Position Sensor (CPS)
• Manifold Absolute Pressure Sensor (MAP)
• Idle Air Control (IAC)
• Intake Air Temperature Sensor (IAT)
• Wire Harness Assembly
• Check Engine Light (MIL)
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 Visteon
Engine Control Unit (ECU) which manages system
operation, determining the best combination of fuel
mixture and ignition timing for the current operating
conditions.
An in-tank electric fuel pump is used to move fuel from the
tank through the fuel line and in-line fuel filter. The in-tank
fuel pressure regulator maintains a system operating
pressure of 39 psi and returns any excess fuel to the tank.
At the engine, fuel is fed through the fuel rail and into the
injector, which injects into the intake port. The ECU
controls the amount of fuel by varying the length of time
that the injectors are "on." This can range from 1.5-8.0
milliseconds depending on fuel requirements. The
controlled injection of the fuel occurs every other
crankshaft revolution, or once for each 4-stroke cycle. The
total amount of fuel needed for one firing of a cylinder is
injected during each 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 air temperature, manifold absolute pressure,
engine temperature, engine speed (RPM), and throttle
position (load). These primary signals are compared to the
programming in the ECU computer chip, and the ECU
adjusts the fuel delivery and ignition timing to match the
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 “ON” and 5
seconds at “OFF” in sequence 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 Polaris Diagnostic
Software (dealer only).