Doosan D20S-5 Operation & Maintenance Manual page 129

Basic Troubleshooting(LP)
The G430FE fuel systems are equipped with built-in fault diagnostics. Detected system faults can be
displayed by the Malfunction Indicator Lamp (MIL) and are covered in the Advanced Diagnostics section.
Items such as fuel level, plugged fuel lines, clogged fuel filters and malfunctioning pressure regulators may
not set a fault code by the Engine Control Module (ECM).
Below are basic checks that should be made before referring to the Advanced Diagnostics section, if engine
or drivability problems are encountered.
Locating a problem in a propane engine is done exactly the same way as with a gasoline engine.
Consider all parts of the ignition and mechanical systems as well as the fuel system.
FUEL SYSTEM SYMPTOM DIAGNOSTICS
Checks
Before Using
This Section
Fuel System Check
Visual and Physical
Checks
Before using this section, you should have performed On Board Diagnostic (OBD)
Check and determined that:
1. The ECM and MIL are operating correctly.
2. There are no Diagnostic Trouble Codes (DTCs) stored, or a DTC exists but
without a MIL.
Several of the following symptom procedures call for a careful visual and physical
check. These checks are very important as they can lead to prompt diagnosis and
correction of a problem.
1. Verify the customer complaint.
2. Locate the correct symptom table.
3. Check the items indicated under that symptom.
4. Operate the equipment under the conditions the symptom occurs. Verify HEGO
switching between lean and rich. IMPORTANT! Normal HEGO switching
indicates the fuel system is in closed loop and operating correctly at that
time.
5. Take a data snapshot using the DST under the condition that the symptom
occurs to review at a later time.
• Check all ECM system fuses and circuit breakers.
• Check the ECM ground for being clean, tight and in its proper location.
• Check the vacuum hoses for splits, kinks and proper connections.
• Check thoroughly for any type of leak or restriction.
• Check for air leaks at all the mounting areas of the intake manifold sealing
surfaces.
• Check for proper installation of the mixer assembly.
• Check for air leaks at the mixer assembly.
Check the ignition wires for the following conditions:
• Cracking
• Hardening
• Proper routing
• Carbon tracking.
Check the wiring for the following items: proper connections, pinches or cuts.
The following symptom tables contain groups of possible causes for each symptom.
The order of these procedures is not important. If the DST readings do not indicate a
problem, then proceed in a logical order, easiest to check or most likely to cause the
problem.
Action
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Operation Section