Page 60
TROUBLESHOOTING
ENGINE STALLS AT LOW SPEEDS
ERRATIC ENGINE SPEED
LOW POWER
Possible Cause Correction
1. Code(s) present. 1. Correct cause of code(s).
2. Cylinder cutting out. 2. Isolate cylinder and determine cause of cutting out. Refer to item
8 in ENGINE MISFIRES — NO CODE(S) chart.
3. Idle speed set too low. 3. Check idle setting. Adjust as necessary.
4. High parasitic load. 4. Check for excessive loading due to engaged auxiliary
attachments.
5. Fuel tank vent clogged or partially clogged. 5. Check fuel tank vents. Repair as necessary.
6. Low fuel supply. 6. Check for sufficient fuel in the fuel tank. Check fuel filters, replace
if necessary. Check fuel supply lines for restrictions or air in the
system. Check fuel return check valve for free-moving poppet.
Check fuel pressure and repair or replace supply pump as
required.
7. Defective fuel injection nozzle. 7. Isolate defective nozzle and replace. Refer to item 8 in ENGINE
MISFIRES — NO CODE(S) chart.
8. Defective unit pump. 8. Refer to item 8 in ENGINE MISFIRES — NO CODE(S) chart.
Possible Cause Correction
1. Air leaks in fuel suction line. 1. Check for air leaks. Repair as necessary.
Possible Cause Correction
1. Code(s) present. 1. Correct cause of code(s).
2. Intercooler cracked or leaking. 2. Inspect intercooler, pressure-test, and repair or replace as
required.
3. Plugged fuel tank vents. 3. Clean the fuel tank vents.
4. Restrictions in the air intake system such as
clogged air filter(s).
4. Check for restrictions in the air intake system. Check the air
pressure in the air intake manifold. Replace the air filter and make
necessary repairs to the air intake system.
5. Poor quality fuel. 5. Drain fuel tank(s), clean system and replace fuel filters. Fill tank
with MACK-specified diesel fuel. Bleed system.
6. Low fuel pressure. 6. Check for sufficient fuel in the fuel tank. Check fuel filters, replace
if necessary. Check fuel supply lines for restrictions or air in the
system. Check fuel return check valve for free-moving poppet.
Check fuel pressure and repair or replace supply pump as
required.
7. Improper valve lash adjustment. 7. Adjust valve lash to specified clearance.
8. Fuel-injection nozzle failure. 8. Repair or replace defective nozzle. Refer to item 8 in ENGINE
MISFIRES — NO CODE(S) chart.
9. Turbocharger dirty or malfunctioning. 9. Inspect turbocharger. Clean, repair or replace as required.
10. Exhaust restriction. 10. Check for restrictions in the exhaust system.
11. Low compression. 11. Check items listed under LOW COMPRESSION.
12. Restrictions in intercooler. 12. Perform restriction pressure test. Clean any restrictions.
13. Restrictions in intercooler inlet/outlet tubes. 13. Disconnect tubing and clean restrictions.
5_106_00.bk Page 60 Friday, August 4, 2000 11:17 AM
BDC for engine manuals and specs
https://barringtondieselclub.co.za/
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