Kubota WG1605-E3 Diagnostic Manual page 24

WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, DM
Checks
DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise. A backfire which is heard in the
intake manifold and air stream indicates that the fuel is being ignited in the intake manifold and is a result of a spark igniting the fuel air mixture.
A backfire heard in the exhaust system indicates that there is an over fueling condition or a late spark event which ignites unburned fuel in the
exhaust.
Preliminary Check
Ignition System Checks
Engine Mechanical Check
Fuel System Checks
Checks
DEFINITION: The engine delivers less than expected power. There is little or no increase in speed when partially applying the accelerator
pedal.
Preliminary Checks
Fuel System Checks
Sensor Checks
Exhaust System Checks
Engine Mechanical Check
Additional Check
Backfire
• Refer to Important Preliminary Checks.
• Check for the proper ignition coil output voltage using a 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
• 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 Gasoline Fuel System Diagnosis.
Lack of Power, Sluggishness, or Sponginess
• Refer to Important Preliminary Checks.
• Refer to the Gasoline Fuel system OBD System Check.
• Compare the customer's vehicle with a similar unit. Make sure the customer has an actual problem.
• Remove the air filter and check for dirt or restriction.
• Check the vehicle transmission. Refer to the OEM transmission diagnostics.
• Check for a restricted fuel filter, contaminated fuel, or improper fuel pressure. Refer to Gasoline
Fuel System Diagnosis.
• Check for the proper ignition output voltage, with the spark tester.
• Check the fuel pump electrical circuit.
• Verify proper fuel pump pressure.
• Verify proper fuel rail pressure.
• Refer to the Gasoline Fuel System Diagnosis.
• Check electrical connections at the injectors.
• Check the Heated Exhaust Gas Oxygen Sensor (HEGO) for contamination and performance.
Check for proper operation of the MAP sensor.
• Check for proper operation of the TPS sensor.
• Check the exhaust system for a possible restriction:
– Inspect the exhaust system for damaged or collapsed pipes.
– Inspect the muffler for signs of heat distress or for possible internal failure.
– Check for possible plugged catalytic converter.
• Check the engine for the following:
– Engine compression
– Valve timing
– Improper or worn camshaft. Refer to Engine Mechanical.
• Check the ECM grounds for being clean, tight, and in their proper locations.
• Check the generator output voltage.
• If all procedures have been completed, and no malfunction has been found, review and inspect the
following items:
– Visually and physically inspect all electrical connections within the suspected circuit and/or
systems.
– Check the brake system for sticking or dragging brakes.
1-14
Action
Action
ECM SYSTEM
KiSC issued 12, 2016 A