Super Jet 701 run away motor ( i caught it tho lol )

[Byeai]

ok anyways i just started my complete 62t motor with stock carbs and factory pipe and started up perfectly fine idled great but when i burped the throttle it instantly reved to full throttle so i pulled lanyard and pushed stop button nothing keeps going so i pulled off the plug boots and obviously shut off it did it twice same way i no its a air leak somewhere but i put all new intake gaskets on it so im pretty positive the intake manifold gaskets are sealed and the carb to intake manifold gaskets are sealed i did a helicoil to run a 61x manifold new gasket there only gasket i reused was the exhaust manifold to headpipe gasket anything eles it could be? it ran perfectly fine before i pulled the motor out of the donor ski so i no it ran and didnt run away before

 

[user_error]

id go ahead and replace the head and base gaskets as well as the intake gaskets again. I personally use sealant on gaskets because i hate airleaks, did you use any gasket maker/sealent on them?

 

[98gti]

You're lucky it shut off by pulling the wires for one thing, you're also lucky it didnt shock the hell out of you or fry your coil. I've always been told to pull the lanyard, hit the stop switch, and hit the throttle wide open.

 

[D-Roc]

Leak test it before you tear it down. You could have air in the fuel lines and cold motors need a rich mixture. Richen your adj screws on the carb too.

 

[Byeai]

no i didnt use any gasket maker i used sbt gaskets but i guess it couldnt hurt taking the intake back off and use gasket maker on the gaskets

 

[jetpilot36]

what about the crank seals?would that cause a leak? and also try just choking the carbs with your hand or a rag or something to shut it off.should just pull more fuel into the engine and choke itself.

 

[Byeai]

yea it would cause a leak but i think i found the leak on one of the carbs it self idk till i put it back in the ski and try it

 

[Mdavies_02]

Did a leak-down on my 62t/61x this past week.... Cost me a total of $11. Just bought three drain plugs for Hot tubs, and already had a popoff gauge.

Might want to just do it to save time. I thought it would be much harder than it was.

 

[Byeai]

Dont have a pop off gauge but im savong up for a maniac motor about there

Sent from my SAMSUNG-SGH-I897 using Tapatalk

 

[nightrider05]

Just a heads up...another easy way to kill a runaway motor is to block off the exhaust. Air intakes are not always easy to block off...exhausts are always easy to access on a Superjet, or most any jetski for that matter.


Popoff pressure gauges are rather cheap and are a good tool to have.

 

[Matt_E]

And the easiest way off all to shut off that run away engine is to push the stop button while holding the throttle wide open.
No need to contort yourself trying to block anything.

 

[tor*p*do]

no i didnt use any gasket maker i used sbt gaskets but i guess it couldnt hurt taking the intake back off and use gasket maker on the gaskets

did you use SBT crank seal?
this may be the problem

 

[N3vrSat1sfied]

And the easiest way off all to shut off that run away engine is to push the stop button while holding the throttle wide open.
No need to contort yourself trying to block anything.

Agreed. This also works if it ever happens on the water. You would have a hard time blocking the carbs or exhaust at full speed with the hood on, screaming across the water.

 

[Matt_E]

It cannot happen on the water because the motor will be under load. An air leak run-away can happen only without a load.

 

[N3vrSat1sfied]

Sorry, you are correct. For some reason I was thinking this happened with a 650sx many many years ago but it wasn't a air leak run away. Either way the method you said is what I have always used and seems to be the easiest.

 

[Matt_E]

Hard to remember all that the first few times it happens though, isn't it.

 

[N3vrSat1sfied]

Hard to remember all that the first few times it happens though, isn't it.

For sure!

Byeai your not the only one that pulled plug wires the first time a motor runs away on you. Now you know for next time. Like recommended do a pop off test. If it runs away again use Matt's method to shut it off.

Not sure if you can get the ski to idle but last fall, on SuperN8's ski I had to use this that method a few times, I was able to keep it idle but if you gave it throttle it would run away. Found the leak in the base gasket just by looking and feeling.