Engine RPMS out of control...engine won't shut-off

[Yooper]

I recently purchased a non-running PWC. After some carb cleaning I did get it running. This is where is gets strange. The egine starts and idles at a normal rpm for about a 5-10 seconds and them the rpms climb to about 5,000.
The first time this happened I pulled the kill switch and the engine did not die...so I pulled the plug wires...kept running...I disconnected the battery...KEPT ON RUNNING...until I killed the engine by pulling the choke closed. In all my 2-cycle experience I have never take an engine keep running without plug wires, ignition, or battery connection. What is going on?
Anyone else have experienced this and if so what could be the problem.

Thanks.

 

[sporsterjoel]

try running it without gas. If it runs with no gas maybe ill trade you boats :cheers: LOL. sorry i cant help you, wierd it runs with out plug wires on it????......

 

[sporsterjoel]

also see how unde my pic I list the make mogle and year of my boat. U should do the same, all members do that so others can help figure out your problems witch can be hard to do if we dont know what it is.

 

[timmyboy76]

runaway engine, stud, Motor was running on pure compression. Happened to my 250R ATC once. Go thru carbs again, recheck the gasket/s, lines, filters.

 

[Yooper]

Runaway Engine

Not sure if people believe me...but no B.S...this really happened. More than once. I'm afraid it's going to blow-up. You mentioned a few things...thanks. What was it on your bike that cause this phenomenon?

Thanks.

 

[Tredski]

Same Issues!!

Sounds very much like my issues.See my post from earlier in the week and the replies I got under the '00 Gti.

 

[Yooper]

Runaway Engine

Thanks...I did read your post and the reasons why the engine is runaway makes sense...but no one has provided a clear diagnosis. What have you done to correct your problem.

Thanks in advance.

 

[Tredski]

Runaway engine

Nothing Yet, have a friend that's going to look at it.Few things he mentioned could cause it:carbon build up on top of pistons,clogged fuel filter,a leak in the intake somewhere. He did say a quick fix may be to just turn the idle down so would idle slower out of water.I think mine is going to be build up on the pistons, cause it runs perfect in the water...no missing .

 

[seadoosnipe]

Yooper...Profile please!

I want to respond to your thread, but you at no time list what kind of Seadoo you have............please fill in your profile.......

 

[Naren]

This happened to me once after I adjusted the carb. I am using zoom(a premix of 50:1) and I leaned out my high side screws on both the carbs of my 95 GTX just a 1/4 turn each, to see if I can get a better spark plug reading. I took it for a spin and while going at high speeds I accidently disconnected the lanyard and the doo kept on running. I tried the kill switch but it kept on running so I pulled the choke, which killed it.
I started it back up and got it back to the shore and checked the plugs, one of them was missing the electrode (melted).

My disgnosis is that, leaning the carbs made it run HOT which melted the spark plug tip and the hot plug surface kept on igniting the fuel and kept the doo running. Pulling the choke will put extra fuel in the cylinders and cooled the metal and the doo stopped.
Well, I replaced the plug and adjusted the carb back to where it was and no problems after that.

Hope this helps

 

[seadoosnipe]

Oxygen?......

By pulling the choke, you can say that you flooded the combustion chamber with fuel and cooled off the electrode, but it's normally the idea that you choked it, which means, the motor lost it's oxygen for combustion.

You need 3 things for an engine to ignite. Air, fuel and heat......remove one and the combustion stops.

This is the second post on the runaway engine in as little as a week now. I'm going to have to find the chapter in the manual and try and do some research on this.

When I found it the first time, I remember one quote and that was to not rev the engine out of the water, or it may not rev back down.

I'll be reading about this and re-post my findings................:cheers: