ox66 limp mode

[ttles714]

I Would appreciate someone getting me started in trying to figure out and test what is causing my SX250 (2001) to go into limp mode ... It has a good water stream from the tell/tale. ... and both oil tanks are full (engine and Bilge )

[99yam40]

what are your gauges telling you?

[ttles714]

Gauges all normal .... no warning lights or horns

[99yam40]

do they work properly?
you need to test them to be sure they light up the correct things when the switches call for it.

if the overheat switch shows up on the gauges and buzzer, and the oil level on the motor does too when tested, then you have some other problem going on that is not designed for the motor to do this

[DennisG01]

Are you sure it's limp mode? A better description of what is happening (before/during/after) would help. Also how the engine is acting, RPMs, etc.

FYI, a good tell tale doesn't mean the engine isn't overheating.

[99yam40]

and just because the oil tanks are full does not mean the level switches all work properly.
could be the system thinks it is low due to a wire or switch problem

[ttles714]

S o maybe someone could explain how the limp system works ... What sensors will cause this motor to go into limp mode ??? .... The motor runs fine for a few minutes then just throttles down to 2k RPM ... gauges are fine, horn and lights work ... How does the oil trigger limp ? How does temperature trigger limp?

[DennisG01]

I think you may be misunderstanding the limp mode thing. It needs an "alarm" to set that (although you need to verify your alarm/gauges work properly).

Manually activate the oil level sensor. See if the alarm sounds.

It sounds more like you might have a fuel supply problem. Start by verifying you're getting enough fuel.

[DennisG01]

BUT... let me add a couple questions to my above response. When the RPM's drop, is this in gear or in neutral? What happens when you fully advance the throttle during this time?

[ttles714]

thanks ....activate which oil sensor ?? the remote tank or the engine mounted tank ? will they both activate an alarm ??

[99yam40]

only the one on the motor

[ttles714]

so cruising at 4KRPM just drops down to 2KRPM and pushing the throttle further does nothing .... I am going to check the High pressure pump and the lift pumps as a possible issue ... I an just trying to understand a little better the Limp mode and what causes it ... You are right, in that my issue might be fuel ... Getting back to the oil senders ... Is this correct ?? The sender in the engine mounted tank will trigger the alarm ???? and the sender in the remote tank will show oil level on the gauge ????? Is that correct ??? thank s for your time

[boscoe99]

Two things normally will set RPM reduction mode. Low oil in the main tank. Over temperature.

In some strange circumstances low voltage may cause the alarm to sound and RPM reduction mode to kick in.

[panasonic]

Gauges all normal .... no warning lights or horns

Have you tested the alarm system to see if it is working? Pull the dead man lanyard off the kill switch and crank the engine over...it should alarm.

Perhaps you should get a Yamaha service manual for your engine...it will help answer your questions.