TROUBLESHOOTING
Engine Faults and Torque Limitations
12/05
BY Service Manual
13-5
© 2009 Yanmar Marine International
Torque Reduction Chart Based on Intake Air Temperature
The intake air temperature will limit the torque at 3000 rpm if the air temperature is increasing.
Torque Limitation for Overheat
Protection Mode
In the case of this mode, there are two possible
situations:
If an electronic fault occurs, it will be displayed on
the display-alarm and a P-Code is saved in the
system. These codes can be read with a diagnostic
tester. A substitute value (fixed value until fault
disappears) is activated (coolant temp=110,
fuel temp=90) and a torque reduction occurs. In this
case, the coolant temperature is also limited by the
torque limit which is described in Torque Limitation
for Failed Sensors Mode on page 13-3. The
substitute value of the fuel temperature is fixed at
90°C (194°F)and that sets a limitation of
approximately 75% from the maximum torque
(Figure 13-1).
Figure 13-1
Figure 13-1
If the coolant temperature is over 108°C (226°F),
an audible alarm sounds and engine overheat is
displayed on the instrument panel display. At 120°C
(248°F) the torque limitation is 30% (Figure 13-2).
If the fuel temperature is too high (over 90°C
[194°F]), this limitation is also active for the
overheat prevention as shown in Figure 13-1. From
100 to 140°C (212 to 284°F) the torque limit is
about 40% of the maximum torque. In this case,
there is not an alarm on the instrument panel
display. In both cases, no P-Code appears.
Figure 13-2
Figure 13-2
Engine speed
2000 rpm
2000 rpm
Torque
Torque [N·m]
Intake air
temperature [°C]
Torque [N·m]
Intake air
temperature [°C]
Engine
4BY2-150
4BY2-180
100% (normal operation)
295
30-50
315
30-50
90%
265
60-90
285
60-90
80%
240
100-130
250
100-130
Engine
6BY2-220
6BY2-260
100% (normal operation)
450
30-50
450
30-50
90%
405
60-90
405
60-90
80%
360
100-130
360
100-130