Cub Cadet Challenger 500, Service Manual

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Engine Management System
7 ‐ 5
4) Replacement of the Injector
Warning:
The injector and all associated hardware may be extremely hot.

Shut off the ignition.

Disconnect the negative battery cable to avoid possible fuel discharge if an
accidental attempt is made to start the engine.

Disconnect the electrical connector from the injector wiring harness.

Relieve fuel pressure.

Remove the retaining clip from the fuel injector.

Remove the fuel line connection from the injector.

Carefully clean debris from the interface surfaces. Do not damage seal mating
surfaces.

Remove the injector from the manifold.

Apply a light coating of a lubricant to both the upper and lower injector seal ring of
the replacement injector.

Install the new injector into the manifold. Check that the injector is installed in the
original orientation to maintain proper spray targeting, and that the retaining clip is
properly seated on the injector and the fuel line.

Install the retaining clip after connecting the fuel line.

Tighten the injector mounting to the desired torque as mentioned in the
manufacturer manual.

Tighten the fuel line.

Re-install the injector electrical connector.

Check for fuel leaks with the key “on” and the engine “off.”

Start the engine and verify proper operation.
5) Plugging
Fuel deposits cause plugging resulting in flow shifts over the life of the injector. Fuel
varnish or gumming, a type of injector deposit, is created when certain types of fuel are
heated by high injector tip temperatures at soak (no fuel flow). Deposit build up in the
director holes cause the flow shifts.

Plugging can cause flow restrictions, frictional changes and the collection of other
particles attracted by the tacky surface. The flow restrictions can degrade
emissions and drivability.

Other fuel and environmental conditions may cause crystal or corrosion growth in
the injector and cause a flow shift.

Oxidation stability of the gasoline affects the potential for deposit formation and
must be controlled by the fuel supplier.

Increased levels of detergent additives reduce the rate of injector plugging.