engine not turning off

[MASTERBrian]

This past weekend while at the lake all was well, 2nd outing in new to me project pontoon with1990 50hp Johnson on the back. The first several times, I went to shut the motor off, it turned off, but later in the day, there were several times when I'd go to turn the key off and the engine would stay running. It did seem to get better, but I'm curious, what might cause this. No I need a new ignition switch?

 

[sam am I]

You could, check the wiring at the back of the Ig. first, something could be loose. Mag Ig's ground the CDI's to kill the spark, sounds like your ground(wiring and/or contacts) to the CDI is flaking. If you're comfortable, jumper the two posts at the back of the switch that kill the motor when it's flaking out to verify it is or is not the switch and go from there......GL

 

[MASTERBrian]

I checked the wiring and all the connections seem tight, but the wire was twisted. Apparently when someone threaded the Ig they allowed the entire assembly to twist. I untwitsted it, but ended up just ordering a switch for $17. I really think it was something in all of that, as a few times, it seemed to turn off, if I'd just work the key a bit.
How do I know which wires to jump? What if it won't shut off at the lake? Can I just pull the gas line? ...my understanding is you don't really want to run a 2 stroke out of fuel.

 

[sam am I]

If the wires are all still standard/stock as per the factor, on the back of the Ig., there should be a single blk/yel wire attached to a post, jumper that wire/post to the adjacent blk/ground wire to kill the engine.

You can perhaps choke it to kill it as well, or worse worse case, yes, pull the fuel line if you have to. Once or twice pulling the fuel isn't going to hurt it, but I wouldn't maker a habit out of it, no.

 

[Silvertip]

There are two "M" terminals on the back of the switch. Shorting those two terminals will kill the engine. If this doesn't work, there is an "open" in one of the black wires going back to the engine.