4.10
ELECTRONIC FUEL INJECTION
9924125 - 2013 RANGER RZR / RZR S / RZR 4 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:
•Fuel Pump
• Fuel Rai
l
• Fuel Line
• Fuel Filter(s)
• Fuel Injectors
• 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)
• Temperature and Manifold Absolute Pressure
Se
nsor (T-MAP)
• Camshaft Phase Sensor
• Idle Air Control Motor (IAC)
• Wire Harness Assembly
• Check Engine Light
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
Electronic Control Unit (ECU) which manages sys
tem
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
t
ank through the fuel line, to the fuel rail. The in-tank fuel
pressure regulator maintains a system operating pressure
and returns any excess fuel back into 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 fu
el 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. 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
th
e ignition timing by monitoring the primary sensor
signals for intake air temperature, manifold absolute
pressure (load), engine temperature, speed (RPM),
camshaft position 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.
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, acceler
ation, 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 empt
y of fuel or has been
disassembled and repaired:
1. Cycle the key switch from “OFF” to “ON” 6 times,
wa
iting 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 a
nd 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
rec
ommended utilizing the Digital Wrench™
Diagnostic Software (dealer only).
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