Runaway engine....

[seadoosnipe]

I have completed some work on the problems that occur with the runaway engine that several of you have experienced this season. Please click on my link below to the "snipes korner" and go to the last post. You'll find the definition of detonation and there is a PDF file that you can open or save that describes piston condition that leads to this melt down.........:cheers:

 

[scooper77515]

So what IS runaway engine?

I have had them rev and go to redline and stay there for a second or two even when I let off the throttle, is this it? It kept running even after pulling the DESS.

I just assumed the throttle stuck open. It only happened when in gear out of the water, when trying to blow the water out of the exhaust at the end of the day, so from then on, I leave it in N and let the rev-limiter correct it.

 

[seadoosnipe]

.......yeah!

Yes, you may have had a runaway enigne. The manual talks about it a little but only in a small paragraph. It's easy for this to occur if you have a problem with detonation or a build up of combustible carbons on your piston head.

With the 2 stroke, there is some residual of oil left over after combustion that we use for lubrication. When conditions are right, these deposits will ignite and continue to run, even speed the engine up and will cause serious damage to your engine if you don't stop it as soon as you see it happening.

The only way that I know of to stop it is to pull the choke. This does two things. It stops air from reaching the cylinder for combustion and it floods the cylinder with "cold" fuel.

For combustion to take place, you need three things; fuel, heat and oxygen. Removing one of these from the equation will cause the "pre-ignition" or "detonation" effect to stop.

The manual states that our engines are prime for this to occur when running on the garden hose because there is no torque on the shaft to strain the motor............:cheers:

 

[scooper77515]

The manual states that our engines are prime for this to occur when running on the garden hose because there is no torque on the shaft to strain the motor.

It happened the first time on the hose, and once more just out of the water blowing the water out before I cut it off for the drive home.

Since then, I leave it in Neutral and the rev limiter seems to keep it from getting high enough rpms to start this chain reaction.

I will keep my hand on the choke from now on.

I was able to stop it in the past just by pushing the throttle to full accelleration once or twice quickly, which I guess just added a small "cool" charge of fuel, enough to stop the reaction.

SCARY thing to have happen, especially on my new motor

Hopefully the break-in premix helped protect a bit it for those few seconds...???