Electronic Fuel Injection; General Information; Efi Operation Overview; Initial Priming / Starting Procedure - Polaris Sportsman 850 Service Manual

FUEL SYSTEM

ELECTRONIC FUEL INJECTION

GENERAL INFORMATION

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 Filters / Pressure Regulator
• Fuel Line
• Fuel Rail
• Fuel Injectors
• Throttle Body
• Electronic Control Unit (ECU)
• Ignition Coil
• Engine Coolant Temperature Sensor (ECT)
• Throttle Position Sensor (TPS)
• Crankshaft Position Sensor (CPS)
• Intake Air Temperature / Manifold Absolute Pressure
Sensor (T-MAP)
• Idle Air Control (IAC)
• 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
performance.
The central component of the system is the Bosch
Electronic 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, to the fuel rail. The in-tank
fuel pressure regulator maintains a system operating
pressure of 58 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 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 intake air temperature, manifold absolute
pressure (load), engine temperature, 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 to match
the values.
4.20
to maintain peak
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

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 still exists and
should be diagnosed.
Accurate testing of EFI components is recommended
utilizing the Digital Wrench® Diagnostic Software
(dealer only).
NOTE
NOTE