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FUEL SYSTEM
GENERAL INFORMATION
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 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 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 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 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.
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.
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
• 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 Sensor
(T-MAP)
• Electronic Throttle Control (ETC)
• Wire Harness Assembly
• Check Engine Light
4.4
9926806 R03 - 2015 - 2016 RANGER ETX / 570 2-SEAT 2015 - 2016 RANGER 570 CREW Service Manual
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 may still exist,
and should be diagnosed.
Accurate testing of EFI components is recommended
utilizing the Digital Wrench® Diagnostic Software
(dealer only).
NOTE
NOTE
© Copyright Polaris Industries Inc.
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