Sparking issue (Strange test results)

C

Chablis

Location
USA
I have a 94 superjet with OEM ignition system.

All summer I have been chaing a catrb issue, but with a recent OEM carb rebuild kit all was running great.

Started loosing high speed about 1 week ago. This last weekend, it started to sputter real bad.

Pulled the kill switch to confirm that was not the issue. Also tried new plugs.

While I was looking for intermitted weak spark, I lost the ability to even start.

Here is the strange part.

With both plugs installed no start.
With one plug in and the other plug wire disconnected no start
With one plug in and the other plug out and not grounded no start.
With one plug in and the other plug out but grounded it fires right up on one cylinder and there is no spark on the pulled plug. As soon as I remove the ground it dies.
Since both plugs should fire at same time I moved the installed plug and wire over to second cylinder. Everything repeats.

I have not run a resistance check boot to boot yet.

Is this normal behavior for a two stroke that both plugs need to be grounded?

If yes, why would it run only when the non sparking side is pulled and grounded.

I have read that the OEM Jet Ski Coil is cheaper but interchangeable with the SJ. Still looking for a PN, but before I order I need to confirm plug to plug resistance.

Anything else come to mind with above fact pattern.

tks
 
C

Chablis

Location
USA
Do you mean shortening the plug wires by trimming off the wire inside the boot.

I have not.

Would I just crimp on a new terminal?

I thought the resistance test may pick up on fractured, but it seems common testers are not sensitive enough.
 
C

Chablis

Location
USA
Thanks for Reply. If boots are not screw on, then I guess my option is to cut the wire and install new boots. Is this the recommendation before going further as a way to confirm the issue is not the CDI or the coil. I could cut and salvage the boots as a test setup before the holiday weekend.
 
C

Chablis

Location
USA
Update: I installed two NGK TB05EmA's For the side with no spark, I found there was a break about 1" back. I was hopeful I would have the ski running for the holiday. I was very careful to make sure a screwed the boots on completely.

I was able to get the ski started but it was very rough. I killed the engine and pulled the plugs to look for spark.

I still had no spark on one cylinder and a very week spark on the other.

Re installing the plugs, I was not able to get the ski started again.

So now that I ruled out the boots, what would be next.

Should I try to install new plug wires all the way back to the coil by removing the epoxy holding the plug wire onto the coil.

Should I just get a new coil, even though most feedback is these are normally not the issue.

Should I get a new CDI.

I did forget to bring an ohm meter to the lake, so was not able to verify resistance from one plug boot to the other.

tks
 
Harbor

Harbor

Location
Stockton
The break in the cables causes engine stutter, which you had reported early on…

Doing your testing with the spark plugs ungrounded may have damaged the cdi…

Have you done a compression test on it yet? Just to rule out top end damage before going further. When compression is low, they don’t like to start and run

Back to your spark issue, I’d ohm out the stator per the service info and get a known good cdi

I have a known good cdi, good for testing, meaning it works to start the ski and can ride fir maybe 1/2 hour or less before it’s starts acting up.. you could barrow it if that would help

In the tech section is service manuals you can view, I forget if you’ve already found those
 
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