150 TXRC 'Safety Mode'

[Psalm 99]

This is a carbed 2-cycle engine with about 600 hrs. Left port today and ran @3300 rpm nicely for about ten minutes until engine quickly went into 'safety mode': 1600 rpm. No warning light or buzzer @ helm and engine running smoothly but would not exceed 1600 rpm. Shut down engine & checked for something obvious. Plenty of oil in engine tank, cylinder heads were not overly hot, water pump working well, no loose wiring. Engine started right back up and responded nicely to throttle (3300 rpm again). Headed back to harbor and with-in five minutes engine flipped back into the 1600 rpm mode. Left throttle set for 3300 rpm and about two miles from harbor engine snapped back to 3300 rpm and responded well to throttle thru docking. I've seen this problem and, once the ground wire connections were cleaned, problem went away. However, its only been about a year since this first happened and at that time, all the grounds were disassembled, buffed, sprayed with CRC electronic cleaner and reassembled. One sort of weird thing: Engine held steady @ 8 mph with 1600 rpm in 'safe mode'. Normally, I'd go at about 1900 rpm to get to 8 mph. In 'safe mode' engine runs smoothly, doesn't smoke or show any signs of stress; just like it did before this started happening. I'm cleaning the electrical connections again but any suggestions of what may also be wrong will be appreciated.

[boscoe99]

Does not sound to me like the motor is in RPM reduction mode. If it were, the buzzer would be sounding and if the tachometer had lights or icons they would be illuminated or flashing.

Low voltage will also put the motor into RPM reduction mode but the buzzer will sound and the lights/icons will do their thing.

[99yam40]

No such thing as safe mode on a motor.

There is a RPM reduction that can happen from low oil level or overheat happen, but it also sets and alarm and sets indicators on the gauges to tell you what is going on.
1st thing I would do is check the alarm system to see if level and overheat sets the buzzer and indicators as they should.

then check to see if there is spark to all plugs when this happens.
the check timing as it happens.
If all of that is good it seems it would have to be a fuel problem

[boscoe99]

No such thing as safe mode on a motor.

You are absolutely correct. I wonder where that saying originated.

Anyone that continues to run a motor in the RPM reduction mode, or in any other mode where the motor is not operating normally, does so at their own peril. The wife ruined her SUV because she did not want to stop alongside the freeway when the over temperature light came on. Better to ruin the engine than be inconvenienced I suspect was her warped thinking.

For 99.999% of the boaters they would be better off if the motor came to a complete stop if a problem arises. I suppose that the lawyers make the engineers design it so that it can be operated in an emergency, recognizing that it might be better to burn the motor up rather than getting run over by a ship.

[pstephens46]

I'd feel so much more safe at 4000 rpm myself.

1600 barely gettin it....

Dirty carbs, nasty fuel.....

[Psalm 99]

Terminology was wrong. I agree the motor is in RPM reduction mode. My understanding is that this is designed to happen automatically when something is amiss (overheating, low voltage, no oil). Its definitely in this mode, it does not vary in RPM (no throttle control above 1600 rpm). Good throttle control right up to 1600 rpm then nothing past this point; unless it just snaps out of this mode. Then it goes right back up to the correct rpm for the throttle. My guess is that there is nothing wrong with the engine (its smooth, quiet, powerful, no vibration) as there no warning (lights, buzzer) at the helm. But rather that some electronic device which receives a signal when there is a problem and places the engine in RPM Reduction Mode is faulty. Engine started right up and ran smoothly (idle thru 2300 rpm) when I got home and put it on muffs.

[99yam40]

If it was in RPM reduction mode there would be an alarm and indicators on the gauges.
unless all of that is broke.
and from what I understand it limits the RPM to 2K not 1600

as I said see what works

[boscoe99]

The number one rule when the motor goes into RPM reduction mode is to turn off the motor.