Problem summary
The engine reaches firing speed, then the governor commands fuel reduction before the start sequence completes. Available start-air pressure is within the expected range.
DG No.2 start failure
Logged
Today · 14:08
Mode
Standby start
Engineer
2/E D. Okafor
Engineer observation
DG reaches 700 RPM during starting, governor pulls the fuel rack back and Start Failure occurs.
Evidence attached
4 items
START FAIL 14:08
Governor linkage
PDF manual
Yanmar 6EY18AL Operation Manual
Measurement
Start air 27.8 bar
Technical assessment
Evidence-based preliminary guidance
Most likely causes
1
Governor actuator feedback mismatch
Position feedback may not follow commanded fuel during transition through 600–750 RPM.
2
Fuel-rack linkage resistance
Binding or delayed return can trigger protective start-failure logic.
3
Start sequence permissive input
Review start-failure relay and governor-ready input status.
Diagnostic steps
0 of 3 loggedConfirm start-air pressure remains above 25 bar.
Observe governor actuator command during 600–750 RPM.
Inspect fuel-rack linkage for sticking before a repeated start attempt.
Measurements to check
Point
Expected
Observed
Start air
>25 bar
27.8 bar
Actuator feedback
0–100%
Record
Safety notes
Keep personnel clear of linkage travel. Verify turning gear, local emergency stop, and fuel shut-off status under vessel procedure before inspection.
Recommended action
Perform a stationary linkage movement check, then capture actuator command and feedback during one controlled start attempt. Escalate to the electrical governor circuit if mismatch exceeds the manual tolerance.
Confidence level
82%