97GTX high revving/wont shut off

[RLB II]

Winterizing my 97 GTX yesterday and after fogging/fuel stable, while it was running I turned the fuel off to run it out of gas. After 10-15 seconds the RPMs went way up and wouldnt drop down when I played with the throttle, so I tried to shut it down. Neither the start/stop button or yanking out the DESS lanyard shut it down, and it continued to run for another 15-20 seconds at high RPMs until it ran out of fuel. Turned the fuel back on, fired it back up and it ran and shut down fine. Repeated the fuel starvation and it did the same high revving/no shut down thing.

Ive run the ski out of fuel before while riding and never had this type of issue. And this is the first year Ive decided to actually run it out of fuel while winterizing at a friend of mines suggestion.

Is this high rev/no shut down normal while running the ski out of fuel as I described? Or am I developing an MPEM issue?

Thanks.

 

[crisso]

As the fuel starts to run out,you develope a "lean" fuel /air mixture.This will increase the revs.The only thing you may have been able to do was to hold the choke on.This would decrease the amount of air getting into the motor.With the "lean' mixture going in,the internals get hotter because of less fuel and oil,and the motor will diesol.That is,it will keep burning what is getting sucked into the motor.
Me? I would restart the motor with all the fuel back on to get it running right.Then refog the motor .2 stroke motor need fuel and oil so they do not seize up.Don't run it out of fuel again.Put in fuel stabilizers so it gets into the carbs/motor etc.

 

[LouDoo]

High revving is usually a sign of an air leak, and since it only does it when you have shut the fuel off the first place I would look it the fuel selector valve. They're cheap to replace if you need a new one, WCS has them for about $20.00. Yes the engine will rev. higher just before it runs out of fuel because of a temporary lean condition, but not run away like you are describing.

Lou

 

[crisso]

Thank you Lou.You still teach me.

 

[RLB II]

Thanks for the replies. It did make sense to me that the RPMs would come up as it ran out of fuel. Ive seen that in other boat motors, lawn mowers and such. But the "run away" as you called it when it wouldnt shut off was very unerving. So that would be an indicator of another issue? And if so what are your thoughts?

 

[LouDoo]

Thank you Lou.You still teach me.

Actually Criss you were also correct, if valve had not been turned to the off position the problem probably never have occurred. I personally do turn the valve off for winter storage but I don't let the ski run out of gas completely.

Lou

 

[crisso]

Like Lou said.Have a look what his thoughts are.3 posts back

 

[RLB II]

Gotcha. The runaway was most likely caused by a faulty fuel selector letting air in when it shouldnt have.

Just thought the start/stop button and/or DESS would overide any type of issue and shut it down.

 

[Bills86e]

Also pincher the RV cavity oil line, A full gas tank will not Oxidize the gas, but blue Marine Sta-bil is recommended. Remove your battery and
keep on your Tender. I like the Optima 4, as it also de-sulfates as it runs automatically to keep fully charged.

 

[LouDoo]

Gotcha. The runaway was most likely caused by a faulty fuel selector letting air in when it shouldnt have.

Just thought the start/stop button and/or DESS would overide any type of issue and shut it down.

Not necessarily because when the engine runs away from a lean condition it acts much like a diesel engine and killing the spark will not have an effect. If the problem happens the best thing to do is open the fuel valve and pull the choke and this will cut the air intake and add more fuel, overcoming the lean condition.

Lou

 

[RLB II]

Thanks Lou. Probabaly shouldnt have ran it out of fuel by the sounds of it. Going to play with it today and run it for a while to see how it acts, before refogging and finishing winterizing. Hopefully all will be normal and I wont run it out of fuel again.

Thanks again for the replies.

 

[470]

I always run the gas out of my carbs. I don't want any fuel to go bad and leave deposits in the carbs. Yes the r's go up when it's runs out of fuel but you can keep them down by using 2 cans of fogging oil. Use a can in each carb at the same time till the carbs run out of fuel.