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Discussion Starter · #1 · (Edited)
Hi everyone, I bought a 1998 MXZ 440 fan cooled for my gf this summer, the seller told me the sle had a bad CDI/Coil.
I put a Kimpex CDI from a 1997, because the '98 was discontinued. I cleaned up both carburetor because it was sitting with 87 in the tank and the carbs was full of varnish. 2 pulls and it started right up, idled and worked well overall. Every week or so, I went and started it. A month in and it's harder to start and will only run on one cylinder until higher RPM. It was not firing on the PTO side, I swap the spark plugs, still the same, swaped the wires, still the same, swaped the carbs and now the MAG side won't fire. I bought a kit and rebuild both carburator. I adjusted them within Ski-Doo specs and I can even start it. I did the troubleshooting following Ski-Doo shop manual for this sled. I finally suspected the stator. It was having weak spark. I went ahead and replace it.

It was back ! I ride it for an hour and it was running good ! The idle was rough, I decided to adjust the carbs the next day. Today, still the same issue it will not start, not even a cough.. I'm lost.. Maybe I'm missing someting simple ?

To resure what I did/know;
  • New CDI
  • New Stator
  • Rebuild/Cleaned/adjusted Carburetors
  • Compression is at 120PSI both cylinders
  • Tried 3 new set of spark plugs ( BR8ES/BR9ES)
  • Cut 1/4 inch of spark plug wire each side
  • Good Battery/Clean ground
  • Switch, tether, kil switch OK
  • No change when I spray brake cleaner close to PTO crank seal

Thank you.
 

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Discussion Starter · #2 ·
I'll try to do a leakdown test this weekend to see if all the crank seals are in goo condition. Also, I thought about a cracked carb boots, I'll take a closer look.
 

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Discussion Starter · #4 ·
try starting it with little bit of gas pour into cylinder. if it fires, u got a fuel issue if not ohm check coil pack and spark plug cap.
Id start from there
I tested the spark plug cap and spark plug wires, the ohm is whitin spec for both. I tried to pour fuel into the cylinder before I replace the stator and it did noting. The coil is in the same box as CDI on this model, the shop manual doesn't recommand to test the voltage of the coil.
 

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Discussion Starter · #5 ·
I double checked the wiring, gapped the plug to 0.018", inspected the carb boots and saw no cracks. Disassembled and cleaned the fuel pump, the diaphragm look good and it can hold pressure. Poured some gas in the cylinders, nothing... I checked for spark and grounded both spark plugs to a head bolt, I have spark....

I begin to think that my brand new cdi could be bad ?!?

I know it has good compression, I know it has fuel and it seems to have good spark.

After running good for more than an hour when I replace the stator, now it won't do anything when I pull the rope or turn the key.
 

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Discussion Starter · #7 ·
I think my sled had same issue. try draining ur fuel out and let the engine dry to check if there is any water contimination, I heard if you pour some gas into clear jar you can check for seperation but I just cleaned out the tank.

u dont check voltage on the coil, you gotta check resistance.

how is your spark plug after giving it couple of crank?
I'll drain the fuel tank, it can't hurt.

I tested the resistance for the coil, plug cap to engine : 1.28M Ohms. Maybe I read it wrong, in the shop manual the resistance should be between 13.1k-18.3k ohms.

I also checked the resistance for the new stator : 253 Ohms.
And for the trigger coil : 165 Ohms.

I checked the air gap between the trigger coil and the flywheel and it's within spec at 0.032".

After a few pulls, both plugs look a bit wet.
 

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Discussion Starter · #8 ·
I went back to do more testing tonight, drained the fuel and put fresh 91 in the tank. Poured some in the cylinders and cranked it. Nothing... Worst it has no spark again..

Put another set of plugs.
unpluged the killswitch, tether and ignition, cleaned the ground wire for this harness, still no spark.
Spark plug cap resistance : 5.5K Ohms
Spark plug wire resistance : 0.6K Ohms
Tested the voltage on the new stator, hit over 30Vac each pulls.
The trigger coil tested has a good resistance reading, but it only showed 0.2Vac. It should be between 2-9Vac from the shop manual.

Each time I installed a brand new elecrical component, It started. Can the trigger coil could be bad too ?

I think I covered all the basics and there's not many untouched component of the ignition system left.
 

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Discussion Starter · #11 ·
View attachment 1986351
Im trying make sure we are looking at the same sheets.
as far as your stator, ohm looks good. check the wattage not voltage tho. but I think its good.
since u already bought cdi and stator, Id just grab new coil and spark plug cap they are cheaper then buying stator alone anyways.
Basiclly the same sheet, I use the spec from the troubleshooting section.
Rectangle Font Parallel Screenshot Pattern


The coil and the CDI are one unit on this sled. Sure I can try new spark plug cap.

Thanks.

Are the plugs wet?
When I do my testing, yes they came out wet sometimes.
 

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Discussion Starter · #14 ·
It might not be related but since I'm going thru the whole electrical system. I found out it didn't had the right voltage regulator. So, I did the swap.
Grass Gas Wood Automotive exterior Fashion accessory

The one for a 440 with electric start is on the right
 

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Discussion Starter · #17 ·
hey! I was sick for a while here. have you try the new trigger coil?
also forgive me if you already said yes, but do you have the spark when you crank it with spark plug grounded to head bolt?
Hey, welcome back haha ! I didn't try a new trigger coil, it's 160$ from BRP and there's not aftermarket equivalent... I've read a lot about trigger coil in general and they're very unlikely to fail. Right now, when I ground the spark plug to a head bolt, I have spark maybe one out of 10 pulls, it's random and it's not a bright blue spark like it was before.
 

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Discussion Starter · #18 ·
I ordered a new CDI/coil unit, I should be able to install it this week. I want to be sure that's not the issue. I also received a brand new fuel pump, just in case and they're cheap anyway...
 

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Discussion Starter · #19 ·
Problem solved !

Before installing the new CDI/Coil I checked all the wiring from the stator to the CDI to be sure that everything was good and that was not the cause for the last CDI to fail. I closed the gap on the trigger coil to 0.017'' and tried to start it again. still no spark. I plugged the new CDI and it started second pull ! It idle great and don't want to stall.

I still don't know if it was a faulty CDI or I did something wrong with the wiring.

Thank you all for your help !
 
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