General Information; Efi Operation Overview - Polaris RANGER 500 2017 Service Manual

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 deliver fuel into the intake. The ECU controls the
amount of fuel by varying the PW (Pulse Width) of the injector signal. This determines how long the injector is open
and releasing fuel, which meters the amount of fuel delivered. 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 sensor inputs such as intake
air temperature, manifold absolute pressure and temperature, engine coolant temperature, engine speed (RPM), and
throttle position. These primary signals are compared to the programming in the ECU software, and the ECU adjusts
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the fuel delivery and ignition timing outputs based on the inputs.
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.
9850043 R01 - 2017-2021 RANGER 500 / 570 Service Manual
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