Yamaha z150 TXRA Runs in Safe Mode intermittently.

[patman60]

My 2002 Yamaha Z150 TXRA runs in safe mode intermittently. This has been going on for several years but has gotten to the point that is is unmanageable. Here are the details - appreciate any suggestion and support.

1 - Sometimes when starting the engine operates in safe mode - no alarms just runs on 3 cylinders. This happens for a cold start or hot start. No over heating no low oil no water in fuel. At first i would have to restart 2 -3 times and it would run normal but it has gotten worse so now it more like 15 plus times. Once running out of safe mode it runs great.

2 - Brought to mechanic and tested the Shift switch - it was good - even took it for a run and played with switch - no difference

3 - downloaded the historical codes

- Code #19 voltage - Assumed this was because the motor was not running. I have no issues with charging
- Code #28 Shift Switch - assumed this was because i had taken it off and run motor with it disconnected from shift linkage
- Code 22 Atmospheric Pressure Sensor - reading 29.4 - accurate for my area that day


So i and the mechanic are at loss for solution. Planning to take it back next week when he has more time.

One suggestion was fuel pressure issues? But motor runs strong and the are no alarm codes for this issue.

Any ideas??

[ausnoelm]

Just because the motor is running poorly, don't just assume it is "safe" mode, let's be perfectly clear here, there is no safe, limp home or any other sort of mode, the motor has an alarm to tell you something is wrong, if you choose to ignore this warning or maybe you're deaf (or the alarm is faulty) it then reduces RPM so only the misinformed then "limp home" a motor running without oil, or badly over heated will surely die, even if it's "limping" in my opinion only of course.

[rodbolt17]

yep
NO limp mode on that motor.
look on your mechanics wall for Yamaha fuel system certificate and electrical at a MINIMUM.

a master tech cert would be even better.

clear the code history, rerun the tests.

if it flags a code attempt to clear it,if it wont clear its is an active code.
you can watch both the shift cut and the shift position working on YDS, it will change on/off states.

other than that its a basic two stroke smoker.
it just has some fancy doo dads that can and will bite you.

[patman60]

thanks for the input - have the engine schedule with a Master tech on monday - will post the outcome

[patman60]

Problemn solved

Found the problem - it was the switch switch after all. In My original test of the switch i made a fundamental error in testing. I tested the switch after removing it - where it tested OK. When installed it was not always being pushed in correctly by the shifter. Lesson learned.

[patman60]

Problemn solved

Found the problem - it was the shift switch after all. In My original test of the switch i made a fundamental error in testing. I tested the switch after removing it - where it tested OK. When installed it was not always being pushed in correctly by the shifter. Lesson learned.