Electronic Fuel Injection; Principal Components; Efi Operation Overview - Polaris Sportsman 800 EFI 4x4 2012 Service Manual

FUEL SYSTEM - GENERAL

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:
• Fuel Pump
• Fuel Rail
• Fuel Line(s)
• Fuel Filter(s)
• Fuel Injectors
• Pressure Regulator
• Throttle Body / lntake Manifold
• Engine Control Unit (ECU)
• Ignition Coils
• Coolant Temperature Sensor
• Throttle Position Sensor (TPS)
• Crankshaft Position Sensor (CPS)
• Intake Air Temperature and Barometric Air
Pressure Sensor (T-BAP)
• Wire Harness Assembly
• Check Engine Light (MIL)
4.10

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
performance.
The central component of the system is the Bosch
Engine Control Management 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. 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
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 can range from 1.5-8.0
milliseconds depending on fuel requirements. The
controlled injection of the fuel occurs each crankshaft
revolution, or twice for each 4-stroke cycle. One-half the
total amount of fuel needed for one firing of a cylinder is
injected during each injection. 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, barometric air pressure,
engine temperature, 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.
9924864 - 2012-2014 SPORTSMAN 800 / 6X6
© Copyright 2013 Polaris Sales Inc.
during operation to maintain peak