4.10
ELECTRONIC FUEL INJECTION
9923523 - 2012 RANGER RZR 570 Service Manual
© Copyright 2011 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 Injector
• Pressure Regulators
• 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)
• Idle Air Control Motor (IAC)
• Wire Harness Assembly
• Check Engine Light
EFI Operation Overview
The EFI system is design ed to p rovide pe ak eng ine
performance with optimum fuel ef ficiency an d lowest
possible em issions. The ig nition a nd inje ction fu nctions
are ele ctronically contr olled, mo nitored an d co ntinually
corrected during operation to maintain peak performance.
The ce ntral comp onent of the system is th e Bosch
Electronic Control Unit (ECU) which manages sys
tem
operation, deter mining th e best co mbination of fuel
mixture a nd ig nition tim ing for the cu rrent op erating
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 f uel back in to th e t ank. At th e
engine, fuel is fed thr ough the fue l ra il an d in to the
injectors, which inject into the intake po rts. Th e 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. The total amount of fuel n eeded 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 ig nition timing by m onitoring the primary sensor
signals for int ake air temperature, mani fold absol ute
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.
During operation, the EC U ha s
the ability to re-adjus t
temporarily; providing compensation for chan ges 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, e tc., a richer air / fue l ratio is
automatically calculated by the ECU.
Initial Priming / Starting Procedure
NOTE: The injection system must be purg ed of all
air prior t o the initial st art 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 time s,
wa
iting for app roximately 3 secon ds at ea ch “ON”
cycle to allow the fuel pump to cycle and shut down.
2. Once step 1 is c ompleted, t urn the key sw itch to
“START”
un til the en gine starts or 5 seconds h as
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 te sting of EF I c omponents is
rec
ommended utilizing t he Digit al Wrench™
Diagnostic Software (dealer only).
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