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4.16

ELECTRONIC FUEL INJECTION

Upper Rear Gearcase Bolt

7. Torque the remaining bolt that attaches the bracket to the

front side of the rear gearcase.

Front Rear Gearcase Bolt

NOTE: A multi-directional torque wrench is required

in this application because of the limited access to

this bolt. Check with the manufacturer of your torque

wrench to see if it can be used to tighten left-hand

threaded bolts.

FUEL INJECTORS

Operation Overview

NOTE: All EFI units utilize quick connect fuel lines.

The fuel injectors mount into the cylinder head, and the fuel rail

attaches to them at the top end. O-rings on both ends of the

injector prevent external fuel leaks and also insulate it from heat

and vibration.

When the key switch is on, the fuel rail is pressurized, and the

EFI relay provides voltage to the injectors. During engine

operation, the ECU completes the ground circuit, energizing the

injectors. The valve needle in the injector is opened

electromagnetically, and the pressure in the fuel rail forces fuel

down through the inside. The “director plate” at the tip of the

injector contains a series of calibrated openings which directs

the fuel into the intake port in a cone-shaped spray pattern.

The amount of fuel injected is controlled by the ECU and

determined by the length of time the valve needle is held open,

also referred to as the “injection duration” or “pulse width”. It

may vary in length depending on the speed and load

requirements of the engine.

The ECU gathers fuel injection timing information from the

Crankshaft Position Sensor and Camshaft Phase Sensor to allow

for sequential fuel injection.

Fuel

Fuel Rail

Injectors

Polaris Ranger RZR 800 User Manual

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