Di run-on

[AZ Sea Doo XP]

Actually AZ is right. when the plugs are hot, the engine will continue running like a diesel. that is something I have personally witnessed.
to stop a carbed engine, you just pull the choke.

 

[AZ Sea Doo XP]

Chester:
the stop button does work.
Thanks

 

[Chester]

Actually AZ is right. when the plugs are hot, the engine will continue running like a diesel. that is something I have personally witnessed.
to stop a carbed engine, you just pull the choke.

I've been working as a PWC repair specialist for over 22 years and yes, I've seen a carbed engine run away many times too. It's called glow plugging. However, it doesn't happen on a DI unless the throttle plate or cable is stuck. This discussion is referring to a DI engine. I've worked on DI engines that would not stop also.
I had my own PWC repair shop for 11 years, worked at a Sea-Doo dealership for one year, and now (for the past 10.5 years) I've been working out of my van as a mobile PWC repair technician. I've seen just about every scenario.

Chester

 

[mikidymac]

I think you are confusing a runaway ski and a ski that won't turn off.
A runaway ski is running wide open with no spark because it is running so lean it doesn't need a spark to fire just like a diesel. To stop a runaway ski pull the choke on an injected ski pull the lanyard or push the stop button and the computer will cut all fuel from the injectors and kill the engine.

The OP said it is idling and won't turn off so this is not a runaway.
As Chester said with it running if the dess post is bad try pushing the stop button as it will kill the engine even if the dess post is bad and sticking.

At idle pulling the plug wires will kill the engine as the spark plugs don't get hot enough to ignite the air/fuel, this isn't a diesel. It has to have spark. Remember if it is at idle it is not a runaway.

 

[AZ Sea Doo XP]

the original question, the last 7 words are the issue: "I had a friend of mine whose Di would not shut off. He removed it from the lake, ran the engine for a few seconds and pulled the key. the engine kept running. he said it took a long time but the engine finally stopped on its own. I wasnt there but what would you do in a situation like that? I had it happen on a carb 951. I pulled the choke and that stopped the engine. I would assume something would have to be wrong for this to happen, but WHAT DO YOU DO TO STOP IT?"

Plugs providing spark, dieseling, running on, running away et al, are not the issue. But, in either case, if you pull the plug wires off on a hot engine, it is very likely it will continue running (I have seen it). so, the engine is running and it needs to be stopped NOW, on a Di how do you stop it? my guess would be pulling the injector wires or the EFI fuse.

 

[Chester]

the original question, the last 7 words are the issue: "I had a friend of mine whose Di would not shut off. He removed it from the lake, ran the engine for a few seconds and pulled the key. the engine kept running. he said it took a long time but the engine finally stopped on its own. I wasnt there but what would you do in a situation like that? I had it happen on a carb 951. I pulled the choke and that stopped the engine. I would assume something would have to be wrong for this to happen, but WHAT DO YOU DO TO STOP IT?"

Plugs providing spark, dieseling, running on, running away et al, are not the issue. But, in either case, if you pull the plug wires off on a hot engine, it is very likely it will continue running (I have seen it). so, the engine is running and it needs to be stopped NOW, on a Di how do you stop it? my guess would be pulling the injector wires or the EFI fuse.

The DI engine will not run away, it will only idle if you can't shut off. Therefore, the engine will not lean out and the spark plugs will not glow plug. So if you just pull the spark plug wires, it will stop.

Chester

 

[mikidymac]

Wow tapatalk is running so slow. Looks like you already figured it out before I posted now all your posts are showing up. Sorry about that. Strange.