'94 25hp 2-stroke Yamaha with intermittent power loss

fototrekr

Recruit
Joined
Apr 2, 2004
Messages
3
Last summer I lent my 16' Lund to some friends to use and it ran low on oil (it has an oil injection system). The alarm light came on and the engine would only go to 2500 rpm while they motored to the other side of the lake to get oil. Since then I've had an intermittent problem that's getting worse....when I run the motor at high throttle, it will periodically lose power down to what feels like the 2500 governed speed and then after 20-60 seconds it will kick into high speed again....the motor doesn't stop, it just goes into a slow RPM mode. I end up starting, slowing, starting, slowing all across the lake. It has gotten progressively worse, however. <br /><br />I read in a repair manual that if the safty governor kicks in due to low oil, that unless it is addressed immediately, the safety system will not return to normal, even after adding oil. Could my problem now be due to the sensor in the oil tank or does it sound like I should get something else checked out? I need to add that when the engine speed is kicked down, I don't see the alarm light on or hear anything. <br /><br />Any help would be greatly appreciated!
 

lonewolf5347

Chief Petty Officer
Joined
Jun 11, 2001
Messages
529
Re: '94 25hp 2-stroke Yamaha with intermittent power loss

fototrekr I would first check the oil level sensor with a multimeter for more details on what step to take in testing the switch e mail me I can end you the info how to test the switch. ;)
 

fototrekr

Recruit
Joined
Apr 2, 2004
Messages
3
Re: '94 25hp 2-stroke Yamaha with intermittent power loss

Lonewolf, that was one of my first thoughts as well but the repair manuals I have been able to find don't go into near that much detail. If you could pass along how to test the oil level sensor with a multimeter, that would be great. You mentioned to send you an email but I didn't see your address anywhere. My email if fototrekr@hotmail.com....if there's someplace on here to get your email, I'd be happy to send one to you first. I'm thinking, however, that it might be as simple as checking for an open vs. closed circuit with the float either up or down? The reason this hasn't been first on my check list is I would think that if the oil sensor registered falsely, my warning light would come on...but it should be a simple thing to test, I presme. If you can share the testing process, I would appreciate it.<br /><br />Thanks! :D
 

fototrekr

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Joined
Apr 2, 2004
Messages
3
Re: '94 25hp 2-stroke Yamaha with intermittent power loss

Lonewolf, I sent an email this am. Thanks!
 

juschuzin

Cadet
Joined
Apr 14, 2004
Messages
10
Re: '94 25hp 2-stroke Yamaha with intermittent power loss

I have had similar symptoms with a couplke of causes, the first was water in the fuel, not enough to easily detect just enought that it sat in the carby and only occasionally would it slow the motor down and seem to lack power, it made me feel stupid but not as bad as the Yamaha Repair shop that took 5 attempts at repairng it :rolleyes: the second time i found the problem was the thermostat had sand in it not allowing it to open properly causing the overheat SLOW speed limiting overheat warning to come on until temperatures were reduced, hope this may help.
 
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