1990 GT, Engine won’t switch off

[Robjjo]

Hi, looking for some help with a 1990 GT. My son flipped it over a few weeks back and despite the tether chord coming off, the engine stayed running. I reached under and pressed the stop button but nothing happened. I then just turned the gas off to which point the engine stopped. Having righted it; we then started it again and the strange thing is I could stop the engine by either removing the tether or pressing the stop button. Any clues?

Also, had been running fine since then, but what prompted this post was that he just called me to say he had just been flushing the engine out and a similar thing happened where he couldn’t switch the engine off by the stop button or removing the tether.

 

[POPPS]

Could becorroded connection because of the water,,, could be a shorted dess post, ,,it controls spark to the rear coil,,,

 

[Robjjo]

Could becorroded connection because of the water,,, could be a shorted dess post, ,,it controls spark to the rear coil,,,

Thanks POPPS, I found out since that it did switch off after flushing; and therefore the issue did only occur when inverted in the water. I am guessing the water must have caused a short but being fresh water vs salt water I am surprised; still what you suggested is the only logical explanation.

 

[Lothsahn]

1990 doesn't have DESS--was introduced in 1996.

The killswitch is just a straight circuit, I believe. You can hold the button in with your finger on the older seadoos.

I'd replace the switch for safety reasons and check the wires for shorts all the way to the MPEM. Also check that no water has gotten into the MPEM box.

 

[POPPS]

Just trying to follow "spock's" advice,,,logic.

 

[Robjjo]

The kill switch I replaced, I will certainly check that no water got into the MPEM box, but I am guessing there is no short as the problem would be a constant. The fact that it only happened when it was inverted suggests that with both switches being submerged that the water itself is somehow triggering the short. Anyway I am less concerned now since I was misinformed about the problem occurring whilst being flushed. But I will give the electronics a good look over. Was curios to hear if anybody else had experienced a similar thing, but then again I don’t know how many of these early models are still out there.

 

[Lothsahn]

The kill switch I replaced, I will certainly check that no water got into the MPEM box, but I am guessing there is no short as the problem would be a constant. The fact that it only happened when it was inverted suggests that with both switches being submerged that the water itself is somehow triggering the short. Anyway I am less concerned now since I was misinformed about the problem occurring whilst being flushed. But I will give the electronics a good look over. Was curios to hear if anybody else had experienced a similar thing, but then again I don’t know how many of these early models are still out there.

Quite a few still out there. Not just us in the forums, but I often seen 1990's seadoos on the lake. Maybe it's only like 10% of the original numbers, but that's still a _lot_ of them out there.

The MPEM box is a plastic case around the electronics. If there was water in there, I could see it shorting things only in certain orientations. Either way, if you verify the wiring doesn't have any cuts or shorts, no water in the MPEM box, and you replace the switch, you really should be good to go.

 

[Camarojoe12]

Any chance you have any engine bay photos? ie; cooling system hoses?