DT75 Help.. Engine misfires/sputters at high RPM

ericgormley713

Seaman Apprentice
Joined
May 3, 2016
Messages
30
Any ideas why it's overheating? The sputter is gone but now the block is getting really hot. 180 degrees. My mechanic took the oil tank completely off. If you have any ideas let me know. Thanks
 

mphelle8vld

Petty Officer 1st Class
Joined
Aug 17, 2005
Messages
321
Water pump, check thermostat, (take note of deposits when you pull it out), I assume your mechanic has checked the timing.

What max rpms and speed are you getting now?
 

ericgormley713

Seaman Apprentice
Joined
May 3, 2016
Messages
30
I took out the thermostat. There was some erosion. I cleaned it and backwashed the motor through the thermostat opening. Fixed the problem of overheating. Mechanic took the boat out previously and there was no sputter. I will check later this week when I take it out
 

ericgormley713

Seaman Apprentice
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May 3, 2016
Messages
30
Took boat out. Problem continues after new mechanic assured me it was the carbs. Possible stater or coil issue?
 

ericgormley713

Seaman Apprentice
Joined
May 3, 2016
Messages
30
Hooked oil tank resivour back up. Filled up with oil. It ran perfect and went up to 19 mph. No sputtering. After 1 minute, limp mode engaged. Im wondering if the oil pump is shot and the oil flow sensor is throwing it into limp mode. Apparently just unplugging sensors does not stop them from going into limp mode
 

mphelle8vld

Petty Officer 1st Class
Joined
Aug 17, 2005
Messages
321
What rpm did you see at 19mph? What rpm did you see after the one minute?

The oil flow sensor only detects a blockage in the supply line or a blocked internal filter.

Not sure what you've spent on mechanics but I still think the monitor gauge would be a good investment.
 

ericgormley713

Seaman Apprentice
Joined
May 3, 2016
Messages
30
4800 then goes to 2800, at that point it appears to misfire or go down to 2 cylinders. Do you know how to deactivate the alarms
 

mphelle8vld

Petty Officer 1st Class
Joined
Aug 17, 2005
Messages
321
Yes, I do...but I don't think you're going to find anyone on a public forum willing to help you torch your motor. The warning system is there for a reason, you have already mentioned the overheating so I would start there. (after getting the monitor gauge)
 

ericgormley713

Seaman Apprentice
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May 3, 2016
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30
I just meant temporarily to pinpoint which sensor it is. I ordered the multi gauge but was wondering so I could get an idea. No worries. Thanks
 

ericgormley713

Seaman Apprentice
Joined
May 3, 2016
Messages
30
Problem was solved. The issue was that I didn't reset the oil alarm on the side of the motor. It runs really well now
 

lakensea

Chief Petty Officer
Joined
Jan 30, 2002
Messages
542
If you think that cured your problem, than you have other issues. The low oil alarm automatically resets when you refill the oil tank. The Low Oil Reset button only works when you need (want) full throttle and do not have any oil on board to refill the tank.
 

ericgormley713

Seaman Apprentice
Joined
May 3, 2016
Messages
30
I changed the engine harness at the same time I reset it so it has to be the harness. There were a couple wires that were questionable
 

ericgormley713

Seaman Apprentice
Joined
May 3, 2016
Messages
30
I've been running it a lot over the past two weeks and monitoring the oil and still using premix. I also installed the multi alarm gauge. I'm nervous about switching to straight gasoline
 
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