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TROUBLESHOOTING GUIDE
When troubles occur, be sure to check simple causes which, at fi rst, may seem too obvious to be considered. For
example, a starting problem could be caused by an empty fuel tank.
Some general common causes of EFI engine troubles are listed below and vary by engine specifi cation. Use these to
locate causing factors.
Engine Cranks But Will Not Start
● Battery connected backwards.
● Blown fuses.
● Clogged fuel line or fuel fi lter.
● Empty fuel tank.
● Faulty electronic control unit.
● Faulty ignition coil(s).
● Faulty spark plug(s).
● Fuel pump malfunction.
● Fuel shut-off valve closed.
● Insuffi cient voltage to electronic control unit.
● Interlock switch is engaged or faulty.
● Key switch or kill switch in OFF position.
● Low oil level.
● Quality of fuel (dirt, water, stale, mixture).
● Spark plug lead(s) disconnected.
Engine Starts But Does Not Keep Running
● Faulty cylinder head gasket.
● Faulty or misadjusted throttle controls.
● Fuel pump malfunction.
● Intake system leak.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
Engine Starts Hard
● Clogged fuel line or fuel fi lter.
● Engine overheated.
● Faulty spark plug(s).
● Flywheel key sheared.
● Fuel pump malfunction.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Weak spark.
Engine Will Not Crank
● Battery is discharged.
● Faulty electric starter or solenoid.
● Faulty key switch or ignition switch.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Seized internal engine components.
66 690 14 Rev. A
Engine Runs But Misses
● Fuel system issue (fuel injectors).
● Engine overheated.
● Faulty spark plug(s).
● Ignition coil(s) faulty.
● Damaged crankshaft position sensor.
● Interlock switch is engaged or faulty.
● Loose wires or connections that intermittently ground
ignition kill circuit.
● Quality of fuel (dirt, water, stale, mixture).
● Spark plug lead(s) disconnected.
● Spark plug lead boot loose on plug.
● Spark plug lead loose.
Engine Will Not Idle
● Engine overheated.
● Faulty spark plug(s).
● Idle speed adjusting screw improperly set.
● Inadequate fuel supply.
● Low compression.
● Quality of fuel (dirt, water, stale, mixture).
● Restricted fuel tank cap vent.
Engine Overheats
● Cooling fan broken.
● Excessive engine load.
● Fan belt failed/off .
● High crankcase oil level.
● Lean fuel mixture.
● Low cooling system fl uid level.
● Low crankcase oil level.
● Radiator, and/or cooling system components clogged,
restricted, or leaking.
● Water pump belt failed/broken.
● Water pump malfunction.
Engine Knocks
● Excessive engine load.
● Hydraulic lifter malfunction.
● Incorrect oil viscosity/type.
● Internal wear or damage.
● Low crankcase oil level.
● Quality of fuel (dirt, water, stale, mixture).
KohlerEngines.com
Troubleshooting
21
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