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Discussion Starter · #1 ·
Good day everyone,

Fairly new poster here, but have been searching and reading tons on this great site.

That being said, my particular problem I've been searching high and low on to find a solution and still have not been successful.

Background:

Around this time last year (Feb 2019), I had my sled on a rally and it was running a bit boggy for most of the trip, then about 5 miles from completion, complete gutless and running on one cylinder. From past experiences, I knew I blew the motor - sure enough pulled plugs and one was coated in silver - hurray. Getting past this, had the top-half rebuilt within a month or so, cleaned it all up nice and shiny and got it back running. But only for short bursts - 2-3 mins at a time, running maybe 4 times total. The last time I had it running I killed it fast as I didn't want to wake my kids who were having nap time - so probably about 10 seconds after it was idling hit the killswitch.

Now for the fun. After this last kill was done, spring had already sprung so I hadn't messed with it much more. But, just for fun and to give it a run cycle, I try starting the sled again. No dice. Pull forever and within the first 10-15 pulls, get a very quiet / low backfire then nothing, completely dead. I figure, well crap - maybe something gummed in the carbs. So I left it again all summer to re-tackle this current fall/winter.

Fall hits, and I get a nice carb rebuild kit online. Carbs are damn near spotless after rebuild and put it back on the machine. Go to try starting, same symptoms - a few pulls, light backfire, then nothing.

Pull plugs to take a look - they were brand new plugs on engine rebuild, so tips are still white but coated with fuel. Inspect further - put plugs into plug boots and check for spark (have to get my wife to pull it over so didn't get a whole lot of umff on pulling over). See some spark, but eventually it fades off, then gone completely.

I decide to try a "Hack" and put a 3/8" chuck into my cordless drill with appropriate size socket that fits onto the clutch bolt - plop the drill in reverse and check for spark myself. Turns at a decent pace - not pulling by any means, but lets me check spark as accurately as I can alone. Same thing - decent spark at first, slowly fading spark, then completely gone. Then what I've found is spark will stay "gone" more frequently now. If I let the sled sit overnight, I can reproduce the spark there for a bit, then gone scenario. If I stay at it for hours, spark will stay gone.

Now - things I've tried:

  • Pulled connectors to kill switch AND handlebars - no change
  • The elusive Stator - replace, clean up oil - no change
  • Trigger coils - never touched or removed them, only unplugged the connector to fit the new stator connector through the crank case - no change
  • Relay- replaced with brand new (NAPA must have caught on to these, got soaked for $30 for a new one!) - no change
  • Corrosion check on ECM Connector/Boot - some corroded pins for sure, but not terrible. Cleaned as best I could with brake cleaner, scraping with wire brushes, scratched female connectors with small piece of wire, cleaned as best as possible, compress air blasted to clean out - no change
  • New Plugs, wires and boots - no change
  • OHM test on DESS POST - within spec for both off and run
  • OHM test on ignition coil primary windings - within spec
  • New Ignition coil - no change
  • Voltage check on primary winding contacts (from ECM) - had I BELIEVE around .2 VDC, but it went away too fast to properly document (to follow main symptom - started with some readings, eventually no readings at all).

Things I'm going to keep looking into:

  • Opening ECM connector to check pins and wiring - corrosion check and voltage check on appropriate pins
  • If absolutely required, new Voltage regulator
  • If absolutely required, new ECM
  • If still no spark - maybe light a match??

I'm posting this as all solutions I've found online were inconclusive for me - "Check trigger coil wiring to be sure its not backwards": spun engine in reverse as per suggestions, no change (also trigger coils were not touched). I'm at my wits end.

Another odd symptom i just noticed was when plugging in the guages, the tachometer needle is sitting right around 1000RPM. When pulling it over for the test, getting no change or light-up on the cluster. Truth be told, I can't honestly remember if it does on pulling over - IE, if the cluster only is supposed to light up / respond on idle or engine run.

I apologize for the novel, but wanted to be as thorough as possible. If anyone has a suggestion as to "HAY DUMMY, TRY THIS" that could save me buying new voltage reg or ECM, I'd muchly appreciate it.

Thanks in advance to all!
 

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wiggle and slightly pull out the Relay above airbag were the 2 amp fuse is, mine has a defective Configuration harness

were that relay plugs in, dealer told me they had problems with a batch of those.Your may be slightly different without electric start

Part numbers are different in BRP parts online.
 

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Discussion Starter · #3 ·
Thanks moresquirt - will definitely give that a go tonight.

Spoke to a used parts dealer / repair shop today as well. He figured if the Trigger Coils OHM out OK the ECM would be the next bet..

Will update my findings!
 

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Discussion Starter · #4 ·
Update to my situation:

I pulled out the relay a bit and by golly, I think that may have helped! I did away with the drill on the primary trick as it didn't spin fast enough. Put plugs against the frame so I could see while pulling, very bright and plenty of spark!

Put plugs back in and pulled.. pulled.. pulled.. pulled.. nothing.

Pulled plugs, COMPLETELY soaked. Had a "derrrr" moment - pulling it over as many times as I have the past few weeks likely filled the cylinders with fuel.

Cleaned off and blasted plugs with air compressor and pulled sled over wide open throttle about 30 pulls with plugs out and killswitch on. LOTS of fuel clouds blasted out of the cylinders. I'm going to let it sit for the day while at work, come back tonight and pull it over another 30 time or so to try get all that fuel out and then I'll put plugs in and give er a go!!

Further update to follow!
 

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ChiefOgemaw
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This won't cost you anything to try, but might be grounding of voltage regulator.

Pull off your exhaust and then loosen your voltage regulator.

Leave the clutch side bolt in tunnel (pita to get bolt started) and remove the bolt on muffler can side.

Regulator has slots in it so it just slides out.

Then flip over, scrape off the bottom, wire brush and sand the bottom and tunnel under mounting area.

Clean ground wire with wire brush and add dielectric grease to everything, both surfaces and re-assemble.

Mine had 1/16" of corrosion in between and wasn't getting a good ground.

Still doesn't want to start when I manually pull unless I hit the RER first. Mine is 600SDI also.
 

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Discussion Starter · #7 ·
Update to my issues.

New find - spark is there. Both on frame and on engine block.

However, still no start.

Since my original post, I found that the carb kit I bough had improper needles. Needles didn't actually "sit" properly causing extreme flooding. It actually flooded the overflow lines through the DPM right into the primary air box. Rectified this by replacing new needles with original needles. Had the carbs apart and did EVERY check - these things are spotless.

Put cabs back on, pull over.. same thing - no start and the odd backfire once in a while.

Other fun fact - when the carbs had the improper needles in, I had my wife hold it wide open and I pulled it over - it started and ran!!!. I had to keep on the throttle and the odd backfire came through (very light) likely due to too much fuel. Once let off the throttle however, sled died instantly and would not start again.

I had my brother over helping, when we were looking at it when pulling over with plugs out (checking for spark), found an electrical arc from mid plug wire to radiator hose!! didn't even look like it went to the hose clamp, but rather the hose itself!! I had these aftermarket spark boosters in place and thought them to be the culprit. Today I pulled plug wires and boots, replaced with NGK red plug wires and boots (solid unit), put new plugs in. STILL NOTHING! Same thing - pull, pull, pull, light pop (backfire), then felt like pulling it over with kill switch on.

SO, tried recommendations above from transformer (pulled VR; VR and frame contact clean), cleaned anyway and put back together. No ground wire noticed or present, but cleaned all connectors with brake cleaner and air blasted dry. Cleaned ground connector that connects to ignition coil i still nothing. Also checked Configuration Cable as per link posted by Doobidoo, no corrosion what so ever (however, "crimped" wires together seems odd to me"), but continuity checked out across the 3 to 1 combined wiring under the duct tape. Still nothing.

I'm honestly starting to think its something so simple and its REALLY bothering me.

I may spend the umpteen hundred dollars on a new ECM just to see if that will put me out of my misery.

Thanks to all suggestions.
 

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Use a timing light to observe the spark and compare pto with mag. Easy, simple and effective. If there is a problem with spark or timing it will be obvious. Note that at no point have I mentioned checking with timing marks. Point it anywhere, ground, wall, seat, doesn't matter.

When starting, spray a fuel/oil mix into each carb. If you fear too much fuel it is counter-intuitive. A no start and backfires are caused by not enough fuel. Once you experience how it works you will find troubleshooting a lot easier and it applies to all engines. Obviously it won't work if the plugs are fouled or no spark.

Spark plugs will foul easy with too much unburnt fuel from a no start. Have someone turn over the engine while inspecting the spark with a magnifying glass. Once you see how it affects the spark, you will gain a better understanding how to avoid it.

Remember that all these no starts are sending raw fuel which washes away the oil film. Even with a mix it still washes, but at least it has oil in the mix. For a rough measure, 40:1 in your mix bottle, and 100:1 in the gas tank.
 

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Discussion Starter · #9 ·
Final Update: Sled is finally running!

Well.. I feel a bit foolish, but at the same time never would have thought it to be the problem.

Piston rings were installed backwards (upside down?? - not 100% sure on what backwards means). Ended up taking it to a local repair shop and he found right away that compression was low on both cylinders.

The reason I never would have thought this an issue is the sled ran, and ran good right off the hop from the rebuild.

I did see other posts about compression issues but again, NEVER would have thought to check it.

Thank you everyone for your assistance and suggestions. In the end, all of the above was performed and a lot of new parts went into this unit - so it's even more "like new" than ever!

I hope this post helps if there is anyone else out there who experiences these symptoms.

Happy riding all
 
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