1998 GSX Limited Engine Problem

[plane_rc]

Hi,

I've just bought a 1998 GSX Limited and after taking it on the water for the first time had a problem when flushing it out after retrieval. Once started it idles normally, but if the trottle is opened even just a little bit the engine revs up and races away toward the max RPM. When I remove the kill switch off the DESS post this fails to stop the engine and the engine continues at high revs until the throttle is pumped, it then throttles back and stops. I've checked the throttle valves and they're not sticking open, any ideas what may be causing this?


I haven't been able to try the start/stop switch to kill it as while i'm waiting for a new start/stop switch (the one that came with it was wrecked), I've been crossing the wires from the start switch to start it, and removing the kill switch to stop.

 

[ski-d00]

the only way to stop engine run away is to pull the choke.

your carbs probably needed cleaned, especially the 2 filters in the carbs.

if you're idle is set too high, this can cause engine runaway on the trailer. a fairly common problem.

 

[Bills86e]

I agree with Skidoo your motor is running lean. If the engine continued to run without the electrical system (i.e. the lanyard was removed), the fuel has to be getting ignited from somewhere. Likely you have some carbon deposits in the combustion chamber that are getting hot enough to ignite the fuel. Carbon deposits are very common in two stroke engines. In addition to rebuilding the carbs, I'd suggest decarboning the engine using your favorite method. You'll likely need to replace the plugs afterward, but you should do that annually anyway. Seafoam.

 

[kustomkarl]

The reason it is running away with high rpm's is similar to a RC,( Radio Control) car or truck, that run on Nitro Methane fuel and only fires on a Glow Plug. The glow plug gets hot and the engine keeps running due to the high temperature of the Glow Plug. The engines are very small 2 stroke, single cylinder engines similar to our 2 stroke seadoo engines. RC's stop when you either plug the exhaust with your finger or stop the fuel to the carb. I own several monster and stadium RC trucks.

Even removing the lanyard or hitting the kill switch won't kill the engine. The choke allows fuel and cool air to enter the combustion chamber and it will stall the firing of the hot fuel in the engine...so it will stall. Both posts above are correct and would cause your problem. Clean the carb and be sure the carbs have a good mating surface so no leaks to run it lean also. I have seen people adjust the idle up because of dirty carbs and it just causes runaway rpm's like this.

Karl

 

[slowboatn]

I'm not sure if this is any help but this is what I was told awhile back when my 98 GTX limited did this. I was told the the cable was too tight to the carb. So when you set idle it really moves that cable. You may need to loosen that up and set your idle then tighten it back down. I agree with all of the above also. Just wanted to throw that out there.

 

[slowboatn]

Mine still does this. I'm going to clean the carbs again and need to know how to do carbonize the combustion chamber while the head is off of it? Any cleaner work or is there something special to use???