Hopfully I didnt just ruin my summer...

[FlightPlanDan]

Check for an air leak by running the ski on the hose, spray carb cleaner around all of the gasket seals while it's running.
When you hit the spot with the leak, depending on where it is, the motor will either bog down or rev up.

(this is just an easier "get started" way than pressure testing)

If it will idle.

 

[Air Biscuit]

Yea that blows. Deff a horrible feeling. At least if it happens again I know what to do. I was like in shock watching this thing rev out thinking this thing is gunna blow. Visions of the summer Ive been looking forward to all winter running through my head and how Id have no engine lol

 

[Matt_E]

Most all engines will do that unless they are tuned very rich at idle/part throttle. I can make all my boats and bikes do it. Next time keep your head and give it full throttle for 2/3 seconds, then hit the stop button. It wont ever happen on the water.

None of my engines do that.

And bingo on stopping them - full throttle while pushing the stop button. Much easier and faster than screwing with the primer or covering the carb.

 

[FlightPlanDan]

Most all engines will do that unless they are tuned very rich at idle/part throttle. I can make all my boats and bikes do it. Next time keep your head and give it full throttle for 2/3 seconds, then hit the stop button. It wont ever happen on the water.

It's true, motors behave differently in the water, with a load, but if it's running away on the trailer....something is wrong.
I wouldn't want to risk my motor each time I rinsed it.


P.S: Air Bisquit, I had air leaks but the ski would run "O.K". But I played hell with carb tuning for about a year. I couldn't screw-out my needles enough to compensate for all of that extra air. Don't beat your head against the wall....check it!

 

[Wave Chaser]

If you changed the Head out you could also have a leak on the head gasket surface

 

[MNTURBO]

If you changed the Head out you could also have a leak on the head gasket surface

yes but that wouldn't be an air leak

 

[FlightPlanDan]

yes but that wouldn't be an air leak

Right, that would be a lack of compression.

 

[SUPERTUNE]

Most all engines will do that unless they are tuned very rich at idle/part throttle. I can make all my boats and bikes do it. Next time keep your head and give it full throttle for 2/3 seconds, then hit the stop button. It wont ever happen on the water.

Its an older west coast head. After assembly I measured 180psi, and I had 93 in the tank

Kev is right with trying to kill a run-on engine! Nail the throttle wide open, at the same time keep pushing the stop button, as soon as the engine get the fuel needs... it shuts right off!
Old school head chamber design with a high squish ratio, stock (lean burn) carbs and the idle screw turned up too far for running ski out of water with no load, ski's will do this all the time!

Just keep the idle screw turned down (out) when running out of the water, until you get in the water with a load, then turn it up as needed.

 

[Patrick Star]

I've seen an engine do it, it's terrible. You just want to run away before the thing blows!!! From what I have seen and been told it will only do it super high without load. If I remember right an unexplanable slightly high idie in the water is also a sign of an engine about to do this on the trailer.

 

[Air Biscuit]

So I haven't had a chance to look at the ski yet but have been thinking about it non stop. Could it have been running off un burned fuel in the cases as if it was flooded from trying to start it? I don't have a choke on the ski, so I was givin it alotta gas. I just can't get over the fact it was running with no spark. I understand dieseling but the ski wasn't running long enough to get hot enough to have another ignition sorce...idk I'll find out tonight what's up.

 

[SXIPro]

A crappy leaky primer can cause the air leak.

 

[Air Biscuit]

I take into conciseration everything I've been told by you guys, im not being oblivious. I just can't get over the fact it was screaming with no spark.

 

[ger87410]

Not 'screaming'. Dieseling. Happens often.

http://en.wikipedia.org/wiki/Dieseling

 

[MADMAT]

Dieseling is how I checked for air leaks on my old motor. I fired it up if it dieseled I knew it had a leak.

Then just stick your foot over the exhaust and it dies right away. :silly:

 

[Pwgsx]

just peg the trottle wide open, it seems like a bad idea but it actually stops the engine. Or keep a damp rag handy and you can wrap the air intake quickly which will also kill it.

 

[Penken]

A crappy leaky primer can cause the air leak.

but primer fitting is on the top part of the carb. which wouldn´t mean squat. tho leaky primer would cause a rich condition?

just peg the trottle wide open, it seems like a bad idea but it actually stops the engine. Or keep a damp rag handy and you can wrap the air intake quickly which will also kill it.

what about a water hose? just put it in the intake. instant hydrolock!

 

[D-Roc]

the run on is from lean mixture and you kill it by flooding the runaway with fuel. i had flooded cases before and it would not runaway but rather backfire, misfire and shoot flames back up the pulse lines.

 

[Midlake Crisis]

I have had loose intake bolts cause this a couple of times.
I don't even freak anymore - I just use the primer method of killing it and it works fast.

 

[KrazyWhiteRich]

so did you figure this out yet?

 

[Air Biscuit]

So I fired it up again tonight after turning the idle down a little. It was idling a little high yesterday before it did it's thing. I took the filters off so i could palm the carbs to kill it this time. It ran fine. Also had decent throttle response for not adjusting anything yet. Any way had it running for prob 5 min reving it everynow and then and it seemed fine. I sprayed some carb clean around the base of the carbs with no fluctuation in RPM. I'll run it a few more times before I put it the lake this weekend.