Doosan D20S-5 Operation & Maintenance Manual page 93

Problem Problem
Rough Idle Rough Idle
High Idle Speed High Idle Speed
Poor High Speed Poor High Speed
Performance Performance
Probable Cause Probable Cause
Incorrect Idle speed control Incorrect Idle speed control
Incorrect timing or spark control Incorrect timing or spark control
Engine Mechanical Engine Mechanical
Incorrect Idle speed control Incorrect Idle speed control
Throttle sticking Throttle sticking
Foot pedal sticking or incorrect Foot pedal sticking or incorrect
pedal signal pedal signal
Clogged fuel Clogged fuel filter filter
Plugged fuel Plugged fuel line line
Air filter Air filter clogged clogged
Faulty vapor connection between Faulty vapor connection between
the the pressure pressure regulator/converter regulator/converter
and the mixer and the mixer
Pressure Pressure regulator regulator malfunction malfunction
Air/Fuel Air/Fuel Mixer Mixer malfunction malfunction
Restricted Restricted exhaust exhaust system system
Incorrect ignition control Incorrect ignition control
Incorrect air/fuel control Incorrect air/fuel control
Incorrect throttle position Incorrect throttle position
-90- -90-
Corrective Action Corrective
See Advanced Diagnostics & See Engine See Advanced Diagnostics & See Engine
Service Manual Service Manual
See Engine See Engine Service Service Manual
See Advanced Diagnostics & See Engine See Advanced Diagnostics & See Engine
Service Manual Service Manual
Check pedal return spring travel for binding Check pedal return spring travel for
See Advanced Diagnostics See Advanced Diagnostics
 
Repair/replace as Repair/replace
See Maintenance section, Fuel Filter See Maintenance section, Fuel Filter
 
replacement replacement
Remove Remove obstruction obstruction from
Close liquid fuel valve Close liquid fuel valve
 
Using caution, disconnect the fuel line Using caution, disconnect the fuel line
 
(some propane may escape) (some propane may escape)
Clear obstruction with compressed air Clear obstruction with compressed air
 
Re-connect fuel line Re-connect fuel line
 
Slowly open liquid fuel valve & Leak Slowly open liquid fuel valve & Leak
 
test test
Check air Check air filter filter
Clean/replace as required Clean/replace as required
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Check connection Check connection
 
Verify no holes in hose Verify no holes in hose
Clamps must be tight Clamps must be tight
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Look Look for for
 
collapsed hose collapsed hose
Test Test pressure pressure regulator
See Engine Service Manual See Engine Service Manual
 
Check Check mixer mixer
See Engine Service Manual See Engine Service Manual
 
Check Check exhaust exhaust system
Measure exhaust back pressure Measure exhaust back pressure
 
See Advanced Diagnostics & See Engine See Advanced Diagnostics & See Engine
Service Manual Service Manual
Operation Section Operation Section
Action
Manual
binding
as required required
from the the fuel fuel line line
kinked, kinked, pinched pinched and/or and/or
regulator operation operation
system