Doosan D50S-5 Operation & Maintenance Manual page 89

Rough Idle Rough Idle
Problem Problem
Rough Idle Rough Idle
the pressure regulator/converter the pressure regulator/converter
and the mixer and the mixer
Pressure regulator Pressure regulator freezes freezes
Pressure regulator Pressure regulator malfunction malfunction
Vacuum leak Vacuum leak
Air/Fuel Mixer Air/Fuel Mixer malfunction malfunction
Engine Mechanical Engine Mechanical
Faulty vapor connection between Faulty vapor connection between
the pressure regulator/converter the pressure regulator/converter
and the mixer and the mixer
Pressure Pressure regulator regulator malfunction malfunction
Vacuum Vacuum leak leak
Air/Fuel Air/Fuel Mixer Mixer malfunction malfunction
Probab Probable le Cause Cause
Incorrect Idle speed control Incorrect Idle speed control
Incorrect timing or spark control Incorrect timing or spark control
Engine Mechanical Engine Mechanical
Verify no holes in hose Verify no holes in hose
 
Clamps must be tight Clamps must be tight
 
Look for kinked, pinched and/or Look for kinked, pinched and/or
 
collapsed hose collapsed hose
Check level Check level in in cooling cooling system
Must be full, check coolant strength Must be full, check coolant strength
 
-35F minimum -35F minimum
 
Check coolant hoses Check coolant hoses
Watch for kinks and/or pinched Watch for kinks and/or pinched
 
hoses hoses
Verify one pressure hose and one Verify one pressure hose and one
 
return hose return hose
Test Test pressure pressure regulator regulator operation
See Engine Service Manual See Engine Service Manual
 
Check for Check for vacuum vacuum leaks
Between mixer and throttle body Between mixer and throttle body
 
Between throttle body and intake Between throttle body and intake
 
manifold manifold
Between Between
 
cylinder head cylinder head
Check Check mixer mixer
See Engine Service Manual See Engine Service Manual
 
See Engine Manufacturers Service Manual See Engine Manufacturers Service Manual
Check connection Check connection
Verify no holes in hose Verify no holes in hose
 
Clamps must be tight Clamps must be tight
 
Look for kinked, pinched and/or Look for kinked, pinched and/or
 
collapsed hose collapsed hose
Test pressure Test pressure regulator regulator operation
See Engine Service Manual See Engine Service Manual
 
Check for Check for vacuum vacuum leaks
Between mixer and throttle body Between mixer and throttle body
 
Between throttle body and intake Between throttle body and intake
 
manifold manifold
Between Between
 
cylinder head cylinder head
Check Check mixer mixer
See Engine Service Manual See Engine Service Manual
 
88 88
Corrective Action Corrective
See Advanced Diagnostics & See Engine See Advanced Diagnostics & See Engine
Service Manual Service Manual
See Engine Service Manual See Engine Service Manual
system
operation
leaks
intake intake manifold manifold and and
operation
leaks
intake intake manifold manifold and and
Operation Section Operation Section
Action