Fuel Injectors; Operation Overview; Fuel Injector Service - Polaris Sportsman 800 EFI 4x4 2012 Service Manual

FUEL SYSTEM - GENERAL

FUEL INJECTORS

Operation Overview

NOTE: All EFI units utilize quick connect fuel lines.
The fuel injectors mount into the intake manifold, 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 voltage is present at the injector. At the proper
instant, the ECU completes the ground circuit, energizing
the injector. 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 (see inset) contains a series of
calibrated openings which directs the fuel into the intake
port in a cone-shaped spray pattern.
The injector is opened and closed once for each
crankshaft revolution, however only one-half the total
amount of fuel needed for one firing is injected during
each opening. 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
from 1.5-8 milliseconds depending on the speed and
load requirements of the engine.
4.22

Fuel Injector Service

Injector problems typically fall into three general
categories- electrical, dirty/clogged, or leakage. An
electrical problem usually causes one or both of the
injectors to stop functioning. Several methods may be
used to check if the injectors are operating.
• With the engine running at idle, feel for operational
vibration, indicating that they are opening and
closing.
• When temperatures prohibit touching, listen for a
buzzing or clicking sound with a screwdriver or
mechanic's stethoscope.
• Disconnect the electrical connector from an
injector and listen for a change in idle performance
(only running on one cylinder) or a change in
injector noise or vibration.
Do not apply voltage directly to the fuel injector(s).
Excessive voltage will burn out the injector(s). Do not
ground the injector(s) with the ignition "on". lnjector(s)
If an injector is not operating, it can indicate either a bad
injector, or a wiring/electrical connection problem. Check
as follows:
Injector leakage is very unlikely, but in rare instances it
can be internal (past the tip of the valve needle), or
external (weeping around the injector body). The loss of
system pressure from the leakage can cause hot restart
problems and longer cranking times.
Injector problems due to dirt or clogging are unlikely due
to the design of the injectors, the high fuel pressure, the
use of filters and the detergent additives in the gasoline.
Symptoms that could be caused by dirty/clogged
injectors include rough idle, hesitation/stumble during
acceleration, or triggering of fault codes related to fuel
delivery. Injector clogging is usually caused by a buildup
of deposits on the director plate, restricting the flow of
fuel, resulting in a poor spray pattern. Some contributing
factors to injector clogging include; dirty air filters, higher
than normal operating temperatures, short operating
intervals and dirty, incorrect, or poor quality fuel.
Cleaning of clogged injectors is not recommended; they
should be replaced. Additives and higher grades of fuel
can be used as a preventative measure if clogging has
been a problem.
9924864 - 2012-2014 SPORTSMAN 800 / 6X6
© Copyright 2013 Polaris Sales Inc.
WARNING
will open/turn on if relay is energized.