Kubota WG1605-E3 Diagnostic Manual page 32

WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, DM
Checks
DEFINITION: A surging or jerking, that follows engine speed, usually more pronounced as the engine load increases, which is not normally
felt, above 1500 RPM. The exhaust has a steady spitting sound at idle, low speed, or hard acceleration, for the fuel starvation, that can cause
the engine to cut-out.
Preliminary Checks
Ignition System Checks
Engine Mechanical Checks
Fuel System Checks
Additional Check
• Refer to Important Preliminary Checks.
• Check the battery condition.
• Check the positive and negative cable connections.
• Check the ECM and system grounds for corrosion at the connectors.
• Check the coil electrical connections.
• Check the air filter for restriction.
• Start the engine.
• Check for proper ignition output voltage, with spark tester.
• Check for a cylinder misfire.
• Verify that the spark plugs are correct for use, with LPG / natural gas.
• Remove the spark plugs and check for the following conditions:
– Insulation cracks
– Wear
– Improper gap
– Burned electrodes
– Heavy deposits
• Visually/Physically inspect the secondary ignition, for the following:
– Ignition coils, for cracks or carbon tracking.
• Wet down the secondary ignition system with water from a spray bottle and look / listen for arcing
or misfiring as you apply water.
• Perform a cylinder compression check.
• Check the engine for the following:
– Improper valve timing
– Bent pushrods
– Worn rocker arms
– Worn camshaft lobes.
– Broken or weak valve springs.
• Check the intake and exhaust manifold passages, for casting flash.
• Check the fuel system-plugged fuel filter, low fuel pressure, etc. Refer to LPG / Natural Gas Fuel
System Diagnosis.
• Check the condition of the wiring, to the low pressure lock-off solenoid.
• Check the DEPR wire harness connection at the DEPR.
• Check the VSW electrical connection to make sure it is fully seated and locked.
Check for Electromagnetic Interference (EMI).
• EMI on the reference circuit can cause a missing condition.
• Monitoring the engine RPM, with a scan tool, can detect an EMI.
• A sudden increase, in the RPM, with little change in the actual engine RPM, indicates EMI is
present.
• If the problem exists, check the routing of the secondary wires, and the ground circuit.
• Check for secondary electrical equipment improperly spliced into the engine electrical system.
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Cuts Out, Misses
Action
ECM SYSTEM
KiSC issued 12, 2016 A