Thread: 96 GTI 720 / 717 No spark
07-21-2011, 09:04 PM #1
- Join Date
- Jun 2007
- California, MD
96 GTI 720 / 717 No spark
SO I bought this ski.....
96 GTI with 720 engine. When I purchased this ski, it needed a solenoid and had no spark. I replaced the solenoid and went on to troubleshoot the spark problem only to find out it HAD spark. I figured during the solenoid swap, I moved something in the electrical box that wasn't making contact. So I went back through the electrical box and verified and cleaned up all electrical connections(none really bad). Didn't see what may have been causing the no spark issue to begin with. So I took the ski out for a test ride. Everything was great...for about 45 minutes.
The ski cut out when I was idling towards my buddy on his ski. Tried to restart...two beeps...cranking over fine...no start. During the 30 minute tow to the ramp I would occasionally try to start it...2 beeps...cranking fine...no start. Towards the end of the tow...2 beeps...crank for about 2 seconds and then stop cranking. If I held the start button it would crank then stop, crank then stop...cycling. Got it home and went to troubleshoot it more the next day.
Put key on and no beeps. Turned out to be the DESS post was bad. Replaced DESS Post, got my two beeps back. Cranking resumed to the crank then stop cycle. However if I disconnect the Black/Red wire from the MPEM to the coil, I get a stready crank. Still no spark. I then ohmed out the ignitor and stator. Ignitor right at 50 ohms. No continuity through Stator...stator wires at 4 pin connector were corroded and not making contact. Hoped the ignitor wires would be bad too, but they were perfect. So I replaced the stator wires and bad contacts. Tried to start again... No change in spark(not that I expected there to be). I have repaired two definite problems, but still don't know why I have no spark.
As I look at the electrical schematic for this ski, I am convinced that it DOES NOT need the MPEM for spark. As far as spark is concerned, the MPEM seems to only be responsible for grounding the primary side of the coil for rev limiting purposes as well as shutting the engine off. CAN ANYONE VERIFY THIS??? Once I get the ski running again, I will test this theory. As for the ignitor...As the engine is cranking, I am able to get a test light to illuminate when connected to the wire going to the coil primary(Wire removed from coil during this check). I have replaced the spark plugs and see the coil as the only possible problem. HOWEVER, I don't see how, in any way, that even when I get my spark back, how am I going to be able to crank the engine for more than 2 seconds with my black/red wire connected back up between the coil and MPEM...Like I said...need that to turn the ski off.
Anybody care to post some thoughtful insight to this? I know there's not a lot of interest here on these older 2 strokes...I've been through every post concerning spark on 720's. Any of the threads that were close to my issue were inconclusive...not to mention dated a few years ago. Someone out there knows...
Thanks for reading. If nothing else, when I do find the problem, I'll post results here for the next guy who experiences the same problem.
08-02-2011, 09:15 AM #2
- Join Date
- Jun 2007
- California, MD
717 720 No spark issue follow-up and Trooubleshooting procedures
Well I guess I know more about these engines' electrical system than at least 59 people! (number of thread views, yet no replies). Here's the follow-up....
My no-spark issue was the coil as suspected. If you have a no spark issue on a 96 and older 717 / 720 engine (and 97-2000 GTS & 97 SP / HX ), troubleshooting is extremely easy.
First..... check the obvious...Spark plugs, wiring and electrical connections. The only critical electrical connections other than the secondary coil wires (Large black ones going to plugs) are the primary coil wire (Black/red) at the coil, and the Black/Red wire at the 4-pin connector going into the front of the engine (Magneto housing).
Second..... Disconnect the Black/Red wire between the MPEM and the coil...ONLY disconnect this wire going to the MPEM here. It is a bullet type connector. Don't disconnect the wire at the coil. Now, try cranking again checking for spark. If you have spark, then the MPEM is bad.
****Recognize here that the MPEM has NOTHING to do with PROVIDING spark, but does in fact take it away. The MPEM grounds out the signal generated by the Ignitor (inside the magneto) to A) stop the engine when lanyard is removed or start/stop button is pressed, OR B) provide rev-limiting. If this internal MPEM circuit is bad, it tends to permanantly ground the signal generated by the Ignitor resulting in NO-Spark. This is also why if the Black/Red wire is disconnected from a faulty MPEM, the spark returns (because you've interrupted that path to ground). This wire must be grounded to kill the engine****
NOTE: IF you decide at this point to ride your ski by simply leaving the Black/red wire disconnected, remember you will not have rev limit protection, and UMmmmm, you'll have to find another way to turn your engine OFF since pressing the start/stop button will only engage the starter!!! (remember, you disconnected the means of killing the engine )
IF you still have no spark after disconnecting the Black/red wire from the MPEM, procede to next step.
With the Black/Red wire still disconnected from the MPEM as described in step 2, Disconnect the spade connector going to the coil. using a multimeter set to AC, or a test light look for indication of power at this wire while cranking. If you have power( or test lamp lights), then you have a Bad Coil. If you do not have any indication of power, the you have a Bad Ignitor (aka generating coil) inside the magneto housing. it is the smaller "single" coil inside the magneto...not the 3 coils that are ganged together(that is your charging coil and has absolutely nothing to do with the spark circuit).
That's it...That is the entire electrical system concerning spark. Hope the procedure helps someone
As for the On-Off Cranking Cycling
Cranking on-off cycling was simply a low battery. When the MPEM detects a lower voltage it cuts power to the starter solenoid. In this case, when the low voltage was detected by the MPEM, it cut power to the solenoid which subsequently de-energized, but as soon as it was de-energized, the current draw stopped, thereby bringing the voltage level above the threshold, and allowing the MPEM to power the soleniod to re-engage.
08-11-2016, 11:21 AM #3
I just want to say I did a google search and this thread came up. I was having an issue with no spark on a 96 Seadoo SPX. This thread helped me out big time! I followed everything rhislo had wrote and it was a bad coil!
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