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Old 28-09-2015, 13:52   #1
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Engine RPM Fluctuation

I have a cat with 2 - Yanmar 75HP motors, SD 40 saildrives and Max props. In larger waves if I set the RPM at 2500 for each the port motor stays dead on at 2500 and the starboard will slow down a couple hundred RPM as it go up each wave. I have had sailboats in the past that would slow down over the waves.
I am trying to figure out if something is wrong with either motor.
Any ideas??
Chris
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Old 29-09-2015, 00:02   #2
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Re: Engine RPM Fluctuation

Bad lift pump or needs filter change?
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Old 29-09-2015, 05:46   #3
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Re: Engine RPM Fluctuation

Greetings and welcome aboard the CF, Chris.
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Old 29-09-2015, 06:00   #4
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Re: Engine RPM Fluctuation

Change your course bearing by 180 degrees...

I kid...

All things being equal...

90% chance of fuel supply issues... Or breathing issues...
10% chance of increased/decreased load issue with the fluctuator...
Tranny/SD, fouling... etc...

But I've been wrong before too....
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Old 29-09-2015, 06:01   #5
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Re: Engine RPM Fluctuation

OH!!!!!!!!

And welcome to CF!
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Old 29-09-2015, 06:08   #6
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Re: Engine RPM Fluctuation

Could be your governor but most problems with diesels are fuel


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