Just picked up a square nose superjet. wont start:(

TurboDon

TurboDon

I picked up a 1990 square nose last week.
started up great when I went to check it out.
Got it home started it a few times to show some buddies... started up and sounded good.
Next afternoon, go to fire it... it cranks and fires for like 1 second then dies. does this repeatedly while i messed with it for an hour or so. Hit the start button, ski cranks, fires for one second then just cranks as if the spark went away.

Next day put new plugs and new fuel in it. Fires right up and runs great. Seems strange but I go along with it.

Now, today (about 4 days later) I go to fire it up and its doing the same thing.
I tried starting fluid, covering the carb with my hand, cranked it with the plugs out and the spark looks strong.

The ski looks bone stock... I dont know a whole lot about it.... it has a 61x head so i suspect someone bored it to a 701 at some point.

Trying to figure this out because we're supposed to be going out to Lake Perris tomorrow morning.
Thanks
 
88kawi5fiddy

88kawi5fiddy

pew pew lazers!
Location
So Utah
unplug the black/white wires and if it runs the start/stop switch needs cleaned. theres a sticky on the main forum page for cleaning how-to.

you will have to pull the plug boots off the plugs to kill the motor with the black/white unplugged.
 
TurboDon

TurboDon

Ok so after messing with it a bit last night I found there to be a strange electrical ghost.

I decided to strip back the two wires that come from the electrical box for the high engine tempurature sensor.
I twisted them together and boom fired right up.... ran like crap almost like in a state of limp mode but ran and fired instantly.
I untwisted the wires and then it seemed to run great.

Took it out to the lake today.
off load the ski and ride it less than 1/4 mile to our day camp area... everything seems normal.
park it for 30 minutes, go to fire it up and it started doing the same thing.

So I drug it a couple of feet up on the shore, took and my tool bag and started playing with stuff.
Tried the trick from the night before of grounding the high temp sensor wires.
This time the ski did something different. It started, would not build any rpm higher than idle and was only firing once every couple of revolutions.
It was so crazy sounding I should have video'd it.
So I proceed to the electrical box. get it all split open take a look at stuff. everything looks tight & dry.
Hmmm weird. So I say what the heck and try to start it.
Boom fires up and I take it out for 30 minutes of trouble free riding.

I'm thinking the CDI has issues but I want to take the stator cover off tomorrow and peak around in there.

Going on a 4 day trip to the river next weekend and want to get this issue resolved before then.
 
Jakobi86

Jakobi86

Te heat sensor will put the motor in limp mode and make it run bad ( in an effort to save the motor) and you accomplished this by twisting the wires together. All that sensor is, is a thermocouple. Either on or off and when in the on position, it's the same as twisting the wires together. Your probably along the right track with the cdi...


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Hobie2356

Hobie2356

Location
Ohio
Before you go on your river trip. Clean the carb, blow out the jets and internal fuel filter in the carb. I would also change the fuel filter. Depending on how long the fuel filter has been in there the cardboard like fibers brake down and will clog the internal filter in the carb.


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Quinc

Quinc

Buy a Superjet
Location
California
I had the exact same issue, it would run fine for a while, but then it was like once it got warmed up it would no longer start. Let it sit for an hour and it would start right up. Pull a plug out next time and see if it sparks when you release the start button. The problem with mine was the stop switch and the msd enhancer where bad/intermittent. Also check (Pull off, clean, make sure it is not corroded or broken) your ground cables. Black wire from stator to ebox, and ground that goes from battery to down by the starter.
 
Sasquachcrap

Sasquachcrap

Location
North Carolina
As stated before check and clean your start\stop switch I had the same intermittent running problem. It was the switch. Cleaning it fixed it for about 4 months then it started acting up again so
I had to replace it.
 
TurboDon

TurboDon

Well its still doing the same thing. after spending several hours taking care of everything mentioned above last night it was running good.
went out today and it was acting up again.
shorted the high temp lead to the cdi and boom fired right up (running like chit tho)
At this point im convinced its the CDI. When it doesnt start, shorting the high temp circuit to ground gets it to fire and run.
Im about to make a drive to go borrow one out of my buddies ski.

At any rate I would like to buy one to have on hand.
What kind do you guys recommend?

It currently has a non OEM cdi in it. Its called a WSM 004 202.
 
kwakhead

kwakhead

Location
macomb
Try getting rid of your heat sensor first-- it may be damaged and what it does is when your engine gets top hot it kills the spark, or will make it run like crap so you're forced to stop riding. That would explain why it runs like crap after its heated up.
 
TurboDon

TurboDon

It was the CDI.

I was trying to track one down locally before my trip and wasnt able to. I bought a 1990 yamaha waverunner III for $200 (has the same 650 engine and electrical as the superjet) So i could pull parts off it.
At any rate, I stole the CDI out of the sit down to get my superjet going and it worked...... for about a day and a half.
Then I was out on the water and everything was going good untill I just died out as if the lanyard had been pulled out.
got toed in and found no spark. after playing with it a while and checking things with my meter I found that I was only getting 4volts AC off of my stator and no voltage out of the CDI on the orange wire that triggers the coil.
checked it with another superjet we had out there and that one makes 31vac.
Pulled my stator and everything looked good visually but apparently that doesnt tell the whole story.

So now I'm back home and I'm planning on now robbing the stator out of the sit down and going from there.

The heat sensor is disconnected and I definitely do not have a fuel delivery issue.
 
cpenn

cpenn

Location
Minnesota
old thread, but for anyone with similar problems here's a quick video on how to determine whether the start/stop switch is causing the issue. Common problem on pre-2021 SJs.
 
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