Kubota WG1605-E3 Diagnostic Manual page 33

WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, DM
Checks
DEFINITION: The vehicle has a momentary lack of response when depressing the accelerator. The condition can occur at any vehicle speed.
The condition may cause the engine to stall if it's severe enough.
Preliminary Checks
Fuel System Checks
Ignition System Checks
Additional Check
Checks
DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.
Preliminary Check
Ignition System Checks
Engine Mechanical Check
Fuel System Checks
• 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.
• Check the fuel pressure. Refer to LPG / Natural Gas Fuel System Diagnosis.
• Check for low fuel pressure, during a moderate, or full throttle acceleration. If the fuel pressure
drops below specification, there is a possibility of a faulty low pressure regulator, or a restriction, in
the fuel system.
• Check the Manifold Absolute Pressure (MAP) sensor response and accuracy.
• Check LPL electrical connection.
• Check the mixer air valve for sticking or binding.
• Check the mixer module assembly, for proper installation and leakage.
NOTE
• LPG / natural gas, being a gaseous fuel, requires higher secondary ignition system
voltages, for the equivalent gasoline operating conditions. If a problem is reported on LPG
/ natural gas, and not gasoline, do not discount the possibility of a LPG / natural gas only,
ignition system failure, and test the system accordingly.
• Check for proper ignition output voltage, with spark tester.
• Verify that the spark plugs are correct, for use with LPG / natural gas.
• Check for fouled spark plugs.
• Check for manifold vacuum, or air induction, system leaks.
• Check the generator, output voltage.
• Refer to Important Preliminary Checks.
IMPORTANT
• LPG / natural gas, being a gaseous fuel, requires higher secondary ignition system
voltages, for the equivalent gasoline operating conditions. The ignition system must be
maintained in peak condition, to prevent backfire.
• Check for the proper ignition coil output voltage, using the spark tester.
• Check the connection, at each ignition coil.
• Check the spark plugs.
• Remove the plugs, and inspect them, for the following conditions:
– Wet plugs
– Cracks
– Wear
– Improper gap
– Burned electrodes
– Heavy deposits
IMPORTANT
• The LPG / Natural Gas Fuel system, works on a fumigation principle, of fuel introduction,
and is more sensitive to intake manifold leakage, than a gasoline fuel supply system.
• Check the engine for the following:
– Improper valve timing
– Engine compression
– Manifold vacuum leaks
– Intake manifold gaskets
– Sticking or leaking valves
– Exhaust system leakage
• Check the intake and exhaust system, for casting flash or other restrictions.
• Perform a fuel system diagnosis. Refer to LPG / Natural Gas Fuel System Diagnosis.
1-23
Hesitation, Sag, Stumble
Action
Backfire
Action
ECM SYSTEM
KiSC issued 12, 2016 A