Diagnostics And Troubleshooting; Engine Won’t Start; Engine Lacks Power; Engine Knocking - Daewoo DE12T Manual

6.1.5. Diagnostics and troubleshooting

Complaints
1. Engine won't start
1) Fuel not being pumped
out from feed pump
2) Fuel not being injected
from injection pump
3) Fuel injection timing
incorrect
4) Injection nozzles
inoperative
2. Engine starts but stalls
immediately

3. Engine lacks power

4. Engine knocking

5. Engine knocks seriously
producing excessive
exhaust smoke
MAINTENANCE OF MAJOR COMPONENTS
Possible causes
® Fuel pipes clogged or air into
1
pipe fine
® Feed pump valve defective
2
® Feed pump piston or Push rod
3
sticking
® Fuel filter element restricted
1
®
Air in fuel filter or injection
2
pump
®
Plunger and/or delivery valve
3
sticking or defective
Injection pump not properly
®
1
installed on pump bracket
® Injection pump tappet
2
incorrectly adjusted
® Cams on cam shaft worn
3
excessively
® Needle valves sticking
1
®
Fuel leaking past clearance
2
between nozzle and needle valve
Injection pressure incorrect
®
3
®
Pipe from feed pump to
1
injection pump clogged or filter
clogged
Air in fuel
®
2
Feed pump delivery insufficient
®
3
® Fuel delivery insufficient due to
4
clogging of fuel tank air breather
®
Plunger worn excessively
1
®
Injection timing incorrect
2
®
Delivery valves defective
3
®
Nozzle leaks excessively
4
®
Nozzle not working normally
5
®
Injection timing too fast
1
® Nozzle injection pressure too
2
high
® Nozzles not working normally
3
®
Injection timing incorrect
1
®
Nozzle Injection Pressure too
2
low
® Nozzle spring broken
3
Nozzles not working normally
®
4
® Plungers worn excessively
5
® Delivery valves seat defective
6
® Supply of fuel excessively
7
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Corrections
Correct
Replace
Disassemble, correct
Clean
Bleed
Disassemble, correct
Check, correct
Check, correct
Replace
Correct or replace
Correct or replace
Adjust
Clean
Bleed
Disassemble, correct
Replace breather
Replace
Adjust
Replace
Correct or replace
Disassemble, correct
Adjust
Adjust
Disassemble, correct
Adjust
Adjust
Replace
Replace
Adjust
Replace
Check feed pump