Engine goes into protective mode.

[Shadow2626]

I recently bought a 1992 Triumph with a Yamaha 150 Ob . The motor ran fine but has now developed an Issue. It wont go over 10 Mph . I had a Mechanic come to the dock and test drive it, We hit a decent sized wave and all of a sudden the Tach started working and it ran 39 mph and ran fine. Yesterday I took it out ran it several miles up the river ,fished and came home ,.On the way home winds kicked up and it got rough, Hit a wave and back into protective mode for a couple miles home. Tach read 30 the whole time it was in safe mode. Im ordering a new tach , but wondering what else may cause it to kick into safe mode , seems like an electrical problem, Any thoughts would be appreciated.

[boscoe99]

Their is no "safe" mode. It is known as RPM reduction mode. Nothing safe about being in that mode. Stop the motor immediately if and when it goes into the RPM reduction mode. Otherwise the motor may be ruined.

Is the complete model of the motor not known? They are not all the same.

What type of tachometer? Needle and dial type or digital display multi-function type? If the latter, what was see on the tachometer when the motor was in RPM reduction mode.

[99yam40]

adding to Boscoe's post, did the buzzer sound when in RPM reduction mode.

a 1992 boat could have any year and model of 150 Yamaha that was ever made

[Shadow2626]

No Buzzer sounding , It is the needle type Tach.I will pull the cowling tomorrow and get the model # .

[99yam40]

Model and serial should be on the mounting bracket

test to see if the buzzer works at all

and I am sure Boscoe was asking for a tach model #

[Shadow2626]

The buzzer does work , the oil sending unit wasnt sending to the reservoir and that buzzer went off , fixed that issue and that is working fine. the tach number is Faria 32805. Can anyone tell me what the adjustment on the tach is supposed to be set to?

[99yam40]

I did not find what I was looking for on the Faria web site, maybe you can look
here is something I did find.
Untitled-3 (productimageserver.com)

did find this,
pic of back of tach.
not sure if it says 5 or 6 for a 12 pole
I am fairly sure that 150 motor is a 12 pole, even if you still have not told us what it is

[99yam40]

I did find the application chart
IS0086J.ai (criboats.com)

Oh yeah, if the buzzer works and it was not sounding while the motor was running poorly, it was not in RPM reduction mode.
I believe that is suppose to sound along with limiting RPM to around 2K

[Keithbaja]

This may not your issue . But I seen this a zillion times.. take off battery wing nuts and toss,in trash.. clean batt studs and cable ends (lugs) install new SS nuts (no locknut's) tighten nuts to a firm position. Not with a 1/2 inch rachet.. this is ABYC standard...
.any one know what color 12 negative cable should be by the CFR's and ABYC