Help! stumped on the King Cat

[stanredrider]

Have a king cat efi that the instant it starts it runs wide open. I know it is the clutch side cylinder that is doing it, just replaced the crank seals and still does it. It overheated on the mountain, so towed it back to trailer. started when it cooled down, and ran wide open. Switched to my spare top end just to be sure it wasnt the cylinders or the head, still no luck. Also switched injectors from side to side. Looking for any ideas before I stick more money in it.

 

[RACINSTATION]

I would guess something is stuck in the throttle body holding the butterfly open.

 

[stanredrider]

Throttle body is closed.

 

[m8magicandmystery]

Throttle body is closed.

with engine off or running..??..the butterfly may for some reason open up when running and all seem normal during a look when shut off..

a runaway can only happen when fuel and air is able to supply the rpm increase.....

if the failure is only during running and no apparent failure of anything when unit is off,well could your box be supplying the one cylinder a full throttle command at idle....(or injector wire grounding or rubbing a live wire etc )..you should be able to use a meter to find that out..??

 

[RACINSTATION]

Throttle body is closed.

Are you looking inside or out?

 

[stanredrider]

Its closed with it off, cant tell if it opens when it is running since I have to shut it down right away might have to try clamping it closed once. Was kinda thinking it might be electrical but still unsure of how it could be getting enough air to take off like that. Thanks for your help so far.

 

[diggerdown]

This is really confusing. Both plugs fire at the same time, so just one side taking it to full throttle seems impossible. Throttle plates are closed, so it can't draw enough air to run full throttle. TPS advances the timing so that could be bad and advancing the timing, but I still don't see how it could rev up that high without enough air getting in. I guess you could try unplugging the tps.

 

[m8magicandmystery]

Its closed with it off, cant tell if it opens when it is running since I have to shut it down right away might have to try clamping it closed once. Was kinda thinking it might be electrical but still unsure of how it could be getting enough air to take off like that. Thanks for your help so far.

so it still takes off to high revs if you take plug leads off mag cylinder..
even if you were drawing air , why the extra fuel..??..nozzles you changed sides so your mag side should have been problematic with the excess fuel when switched....so again a command issue either box or wiring issue..??

if you had air only as an issue and not fuel you would have lean bog issues i would think..can you get air through base gasket..??

Is there any chance that the crankcase has filled somewhat with fuel from a leaking nozzle and your issue is from a static problem rather then a running problem and that if the fuel was diminished that you would return to normal idle...if the air issue is addressed..if there is an issue..

 

[stanredrider]

Yeah it will still run up to about half throttle with the plug lead off the mag cylinder with the throttle bodies closed. The case looked good when I had it apart to replace the crank seals. Only thing I could find out of norm was the flywheel is really magnetized to the stator, so much so that it almost feels like pulling over with compression when the cylinders were off. Stator checked out ok with ohm meter.

 

[m8magicandmystery]

ok..im confused..your first post says W/O and your certain its just clutch side..

and now with your last post im getting the impression 1/2 throttle with the mag plug leads off..

so are we dealing with an issue that is with both cylinders and not just one..that is kinda important to clarify..

 

[m8magicandmystery]

Yeah it will still run up to about half throttle with the plug lead off the mag cylinder with the throttle bodies closed. The case looked good when I had it apart to replace the crank seals. Only thing I could find out of norm was the flywheel is really magnetized to the stator, so much so that it almost feels like pulling over with compression when the cylinders were off. Stator checked out ok with ohm meter.

you got the flywheel key in good..they can be a bit of a pain..lol..

 

[stanredrider]

sorry about the confusion, with both cylinders firing it will go to wide open or further I always shut it down before it goes too far. With just the PTO side firing it is about half or a little better, with just the mag side firing it will barely idle like it should on one cylinder.

 

[m8magicandmystery]

sorry about the confusion, with both cylinders firing it will go to wide open or further I always shut it down before it goes too far. With just the PTO side firing it is about half or a little better, with just the mag side firing it will barely idle like it should on one cylinder.

well with the mag plugs off..and it running at half rpm...can ya spray some wd 40 in possible area's of air inducement to help identify a possible breach..(the wd 40 will cause a change if it finds a breach)...then your air part of the issue may be found..torn boot/seal/gasket..etc..or maybe if your REAL lucky you can still find the breach if your just fired up on the lower rpm mag side if you try it first...

reguardless you find i/2 the problem..if its a problem...lol..

you sure its not throttle body /throttle body sensor/plate related though like suggested by racin station

 

[stanredrider]

Update

Did some more messing around with it tonight, had it running on one cylinder at a time while spraying ether around every possible place for an air leak and no change. So back to not knowing what the issue is, could it possibly be the computer? This one is beyond frustrating, about ready to call it quits and part it out, did get one day of riding in for the year.

 

[arcticridr]

That just makes no sense at all... to make rpm's you need fuel and air .. if the plates on the throttle body are closed you lack one of the key essentials of making it run wide open (air) its prolly not the ecm cus all it could possibly do would be to run the injectors wide open and if the plates are closed you are again missing the air to go with the fuel????? Even an air leak in the case I dont think could supply enough air for that I mean those are 44mm throttle bodies which move a ton of air??? what happened prior to the sled doing this ,, gotta be something even as small as It may seem ?? Blow a belt, replace a component, melt it down ??? Remember the ecm is only going to control fuel in relation to throttle position even if the tps were wacked out its still got to get air from somewhere to do what its doin .. gotta be missing something simple !! I hate it when crap like that happens!! Keep us posted


eric at racin station U rock thanks for the help!!!!!!

 

[m8magicandmystery]

you have to get a look at the throttle body plates when you start it up somehow..the butterfliy has to have an issue opening on its own...???..

 

[stanredrider]

Prior to this happening it was running great, later in the day it all the sudden got hot on me. So shut it down and let it cool, checked the simple stuff and figured I would head towards the trailer. Made it a mile or two and overheated again, so towed it a few miles until the tow sled overheated (what a day). Figured it would make it a mile closer before it overheated so started it up and took off. Shut it down shortly after because I could not get it to slow down and here it sits. Will agree it has to be getting air from somewhere in order to rev up but I cannot figure this one out, will try taping off the intake of the throttle bodies to see what happens tonight. Thanks for everyones help so far and keep any ideas coming.

 

[arcticcatwill]

The throttle bodies might be closed when not running but when it fires up it may be pulling them open, meaning spring not hooked up on it. Is your throttle lever loose at the same time as running? Also did you by chance have the fly wheel off? I put one on and it pushed the key off when it popped on and didnt relize it. Your fly wheel could have spun making the timing off, making it over heat, leading to timing making it rev high. But wide open seems like more rpm than just timing too.

Will

 

[stanredrider]

Throttle bodies operate normal as far as I can tell, the flywheel is alright too, had to pull it off in order to replace crank seal. My thermostat stuck closed is why it overheated, leading to this problem how that would cause this issue is beyond me.

 

[lightcat900]

I would try plugging the throttle body inlet with a rag or something just so you can eliminate that as a variable.