Testing for Spark - How I think you should - And When It Goes Wrong!

Checking for spark on your snowmobile or ATV is a common step in trying to figure out why a motor won’t start. In this video I’ll talk about some of the different ways to check for spark, and show you two examples of what can happen when it goes wrong - Including what happened to me recently.
This video is intended as entertainment, always check with a qualified technician or your sled dealer before attempting any of the procedures depicted on this channel.
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[@shperax]

I've been shocked so many times I am my own spark plug meter. Very accurate also

[@MyOldSled]

I’ll call you next time...

[@GusgusA1]

quite the feeling eh

[@tedthedestroyer9802]

I was checking for spark on my sled a few weeks ago and had the electrode of the sparkplugs DIRECTLY over the plug holes. Then I thought "ya know maybe that's not such a good idea" and moved them somewhere else. Never considered burning the sled to the ground checking for spark before then.

[@MyOldSled]

Fuel vapour is heavier than air, and a belly pan is a fabulous place for it to collect :)

[@bradenshones2423]

I’ve been watching all your videos waiting for it to snow

[@MyOldSled]

Soon......

[@robrovina8223]

Wow - thanks for sharing- I’ve been check plugs that old school way for years.

[@MyOldSled]

Me too.:)

[@ethanfilewych6754]

Another good tip with spark plugs that I learned from my buddy recently is you can take them out and lay them on the ground, spray brake cleaner on the gap and light it on fire and I guess it burns the carbon off. Worked perfect on my 1975 Skidoo Olympic. Now it runs!

[@MyOldSled]

Hi Ethan, I always replace fouled plugs, but if you are going to use heat to burn of deposits, thats a better way to do it than a higher heat source like a torch. You can use a brass wire brush along with that method.

[@lcvt8023]

facts! great warning video! my buddy and I totaled a 06 rev same way. While he ran for a fire extinguisher I had to drag a 8 ft ball of fire out of the garage as the flames were kissing the paper face on the ceiling insulation. scary shit but lesson learned. the garage survived and now I work on shit with a fire extinguisher ready to go. safe wrenching everyone!

[@ponycarfan]

I've always tested spark that way and never had a problem, but I can see why this is such an useful tip. By the way, I knew an old mechanic who "tested" spark by sticking his pinky into the plug cap before pulling the engine over. Don't do that.

[@MyOldSled]

Me too. And i probably will again...but seriously. Think twice. Thanks for watching

[@DBarnim]

Great video David, nice touch of humour to brighten up a snowless winter.

[@MyOldSled]

Hi David. Glad you liked it.

[@alexkunzelman5825]

Lol as you said it hasn't happened yet 🤣 but I think I will change it up before something does lol good stuff David

[@topaze221]

Thank you. Glad you mentioned it was the carb at end of video. I spray a little carb cleaner in cylinder then set plug over hole. If it lights I have spark. No shed or gas around.

[@nicholasconnelly3251]

Happy you ok, your videos have been very helpful to me

[@MyOldSled]

Hi Nicholas. All good. Thanks for commenting. I'm glad you like them.

[@nikolutkauskas5126]

You literally read my mind😂😂 I am having a spark issue on my sled as well.

[@MyOldSled]

Yeah I had a feeling.

[@GPOutdoors]

Thanks David. An excellent piece of advice for us, including some safe alternatives. Cheers!

[@MyOldSled]

Thanks GP

[@Ryan-pc5ue]

I did that with my pontoon several years ago and lit myself on fire. Luckily the boat and I were in the water. Minimal damage to myself. My wife no longer helps with diagnostics lol. Say I have an idea for a video if you deem it worthy. I have been working on a 99 MXZ 600 that sat for 16 years. While getting everything tuned and dialed in, I experienced the dreaded flashing key light. And the sled wouldn't go over 3k rpms. Fortunately it was just a dirty DESS key and the problem was easy to fix. Unfortunately I cleaned and readjusted the carbs three time not knowing that the DESS system was the culprit all along. Love the videos you'r putting out here and thank you!

[@MyOldSled]

Those keys can be a pain. How did the boat make out?

[@Ryan-pc5ue]

@@MyOldSled Oh the boat came out unscathed. She’s resilient.

[@bluntmedia399]

I have a 1998 mxz 670 I've rebuilt just this year, was having random spark failure after rebuild, what i did to find my issue is tap on the cdi and ignition coil lightly with a screwdriver handle, ended up being the CDI. after doing that she fired up, so I replaced it and now she's a one puller every time! couldn't be happier!

[@MyOldSled]

Yeah sometimes just disturbing a part that has sat for a long time, like with a rebuild, will cause a failure to occur. Was probably getting ready to fail for a while. Thanks for watching.

[@alissaharvey7683]

Yes I agree, it has never happened to me but I've seen it happen but because I like doing stuff the old way I will continue to do it the old way, but it is a very good tip for some one that is inexperienced

[@MyOldSled]

Hi Alissa...I know experienced mechanics who've done this.. :) It never hurts to be reminded.

[@albertliebregts1040]

Great video. Somewhat humourous yet very throughly helpful.

[@MyOldSled]

Hi Albert. Thanks for watching. Glad you liked it.

[@italianbulldog3319]

Had my lawn tractor not start before. Luckily I have one of those testers. Even though I had spark the spark plug was defective. New spark plug and good to go. Thanks for the videos.

[@MyOldSled]

Like I said, always start with fresh gas, air blast the air filter, new plug. Almost always works.

[@italianbulldog3319]

Yep you're right!

[@keanbourdon5070]

Let’s all be honest here the one and only David Clarke deserve more subs and everything like that. Love the outro to this vid very nice.

[@MyOldSled]

Lol. Thanks K. Looking at my older content, I’m shocked anyone subscribed, but I appreciate it.

[@jonthelamb4549]

I always leave the old plug in and then I use a different one that I know is good mainly becuase I don’t feel like unscrewing the old one

[@z7117z]

I use a timing light to check for spark. Many times I tried the 'ground the spark plug to the head' method, but could not see a spark, and when using a timing light it was easy to see it was sparking. I find that many parts of the head are painted and do not make a sufficient ground to use the dangerous method you describe. There is an extra step to use the timing light in the event the machine doesn't have a battery (snow blower, old dirt bike etc.) I will have to find a battery to connect the timing light to. Any 12 volt battery I can round up will do (even a lawn mower battery has more than enough juice to run a timing light).

[@MyOldSled]

Thanks for the suggestion

[@keving.4020]

I've lucked out as far as any fire balls. However, I have had my sled make a very loud BANG! I guess you could call it backfire, but has a popping sound. Come to think of it, I've had it happen while the plugs are screwed in as well. Normally its after I first start it cold while going through the priming process, and it'll kind of make a snapping, popping sound. And sometimes will leave a soot ring around the sparkplug hole. Anyone ever had this, and maybe explain a bit? Waiting for snow down here in Maine, have not started season yet. Great video Dave!

[@MyOldSled]

They can backfire if you shut it down while giving it throttle. But theres something wrong if anythings coming out around the sparkplug. Have you tried switching out plugs? Im just trying to understand why its not sealing. You’re getting a puff of smoke with plugs out?

[@keving.4020]

@@MyOldSled Yes, I've seen a little smoke rise when the plugs are out when testing it that way. It may have been they were not properly torqued into cylinder head.?.? But mostly when I start it cold, I give her 4ish primes, pull her over, if I dont get the "almost starting sputter" if you will, ill give her a half prime and sometimes that's when ill get the bang! Its not very often though. Like it will act like shes going to fire and start but almost like it's to much gas from prime maybe and I still get a good spark and she kicks like that. But will always start right after. I'll have to pay more attention now that I'm talking about it in detail. I have a 98 Ski doo GT 583, 2-up. Love the ol girl, I'm a sucker for the older ones.

[@MichelJosephCardin]

When I reached 5:10 ; my first thought was to have a spare plug to thread into the hole; and then do it the old way.

[@MyOldSled]

Definitely better, I think I mentioned that, but still important to be aware that any time a spark occurs outside the cylinder theres a risk of igniting fuel vapour. Thanks for commenting.

[@peeinginthewind]

Glad your okay 👍… lesson learned …I have picked up a barn find 1997 Yamaha vmax 500 aaannnnnnddd no spark 😞.. key on kill switch up .. changed the plugs .. do I need at battery in it maybe to run ? Anything helps guys !

[@MyOldSled]

It should have spark without battery. I don’t really know that sled but I would test simple stuff first. Make sure Kill switch isn’t grounding, check ignition switch, check fuses.

[@philipandlaurareed5731]

Thank you for making these videos. Super helpful.👍

[@MyOldSled]

Thank you for taking the time to comment. Glad you like them.

[@rltkktlr]

Well David you had spark, so what was issue? Bad gas? Lol anyway glad your ok. I still do it old school at times, but yes good to be careful. I will say I really like the inline testers. Obviously it will show no spark, But let’s say your engine starts, but runs badly. Some might, correctly, assume carb issues. Well could be a weak spark, same culprits as a no spark. But once you know what a strong spark looks like you will recognize a weak spark with an inline spark tester. I just had this issue on an old Kohler engine in a leaf blower. Great video. Thanks.

[@MyOldSled]

Carb just needed a thorough cleaning. I took it completely apart a second time cleaned and blew everything out. I think the float was sticking.

[@rltkktlr]

@@MyOldSled that would explain all the gas. Thanks for sharing David.

[@Charlie-wi5gq]

2003 Skidoo MXz. No spark. After checking every possible circuit, ohm'd out stator, all good. Scratched head for a year, decided to pull flywheel. Turned out magnets attached to the flywheel delaminated and were resting against the stator and not turning with flywheel. No electric power generation.

[@MyOldSled]

Thanks Charlie. That'll do it! Thanks for sharing that.

[@tylerBRP]

I have a 98 mxz 670 thanks for all ur help

[@MyOldSled]

Nice sled. I think I prefer my 97 to my 05

[@GusgusA1]

only way to see if the actual plug is working is old school. The other ways just tell if energy is in the wire.

[@MyOldSled]

I would always have had a look at plugs before checking for spark, and as i said normally would put fresh plugs in when problem solving. Depending on plug type, they can fail, but its rare, other than fouling. Thanks for watching and commenting Chad.

[@Ryan-rd9ux]

Where about on the bruce are you located? By the looks if it you have more snow than we do in miller lake. It looks like the groomer was out packing snow from the Lindsey trail south. Just need snow. Great videos.

[@MyOldSled]

About an hour South. Looks can be deceiving. The bottom of my lawn is a lake, the roads are bare, and that snow you can see is mostly just a bit of ice left from freezing rain,

[@aidenmaves5537]

Good to know didnt know this

[@MyOldSled]

Which part Aiden? How to check for spark, or that I'm an idiot?

[@aidenmaves5537]

@@MyOldSledprobably both 😂 jk

[@EmilForsberg_GRYBO]

Ey, congrats on 10 000 subs man!

[@MyOldSled]

Thanks Emil!

[@farmark457]

Same thing with a mini bike when I was a kid, checked for spark and caught fire burning off the fuel line which bled out gas onto my leg,,, so I get what your saying. Thx.

[@MyOldSled]

At least you were a kid...had to add that huh? :)

[@MyOldSled]

Hope you weren't hurt badly.

[@farmark457]

@@MyOldSled Jeans burnt into skin, bad enough but learned my lesson.

[@axetonwright9117]

I have done goofy things like that many times. Just a few weeks ago, I went to start my sled and flooded it, so instead of pulling plugs and letting the gas evaporate, I had a propane torch and stuck the flame in one cylinder. Pretty much blew myself up. It did work, but as an afterthought was pretty stupid.

[@MyOldSled]

Thanks for sharing, makes me feel better.

[@axetonwright9117]

@@MyOldSled we all like to know we’re not the only ones lol.

[@raymondburelle3425]

I always do the old school method easiest way to tell if you have fouled plugs. If my sled is flooded I hold the throttle wide open while pulling it over this usually gets her too start. Now I've got a efi electric start sled and don't have to worry about it

[@MyOldSled]

I would put a fresh plug in a non-starting sled long before I got to checking for spark.Yep, my 600SDI has a flooded mode as well for clearing flooded cylinders.

[@raymondburelle3425]

@@MyOldSled im cheap i carry spare plugs but hate changing em for no reason lol. hate taking em out of the package if I don't need to either

[@MyOldSled]

Oh I wouldn’t put a new plug in if its just flooded. I’d clear the cylinder out and wipe the plugs. I mean a motor thats really not starting.

[@raymondburelle3425]

@@MyOldSled gotcha yeah same here if I don't know the history of the motor and if the plugs look really grungy

[@paulyorke112]

Thanks David good tip

[@MyOldSled]

Thanks for watching Paul.

[@CraigArndt]

I guess I missed how a spark plug grounded to a head or exhaust would ever come in contact with that much fuel. Either way, you can buy a spark testing light on Amazon for $10 bucks or so. Testing spark is just turning over the engine a few revolutions so I just can't see where all that fuel came from, unless the fuel hose was disconnected pointing right at the spark plug wire.

[@MyOldSled]

Well in my case, fuel vapour collected around the motor while i was messing around with it. Once that ignited any fuel in the carb would also ignite. The spark plug was no where near where the majority of the fire was. Important to remember fuel vapour is heavier than air and will collect at a low point, like your belly pan. The second example was a problem with the fuel pump dumping fuel in the cylinder. There are dozens of possible ways i can think of this can happen, and ways to avoid it, like shutting off fuel first. The point of the video is stuff happens, and its easy to forget when you’re frustrated and trying to figure something out.

[@MyOldSled]

Just a thought, the amount of fuel in Dave’s video suggests an abnormal condition, it’s the things we “just can’t see” that usually bite us.

[@jacksoncornish4051]

Great video

[@MyOldSled]

Thanks Jackson!

[@Paisteboy]

That's never happened to me and I've been doing it for years. It makes me think twice of ever doing it again though. lol.

[@MyOldSled]

Lol, same here, until it did. Thinking twice is the main message. Because the fuel isn’t compressed, its not as likely, but as you can see...boom.

[@cartertomlin7105]

Yay u hit 10k subscribers!

[@MyOldSled]

Yeah...not sure how that happened but It's kinda cool.

[@truenorthmuskoka9077]

I was going to say why didnt you use your spark plug tester. I bought one back in 2018 after watching your video

[@MyOldSled]

It was all the way on the other side of the house ;)

[@truenorthmuskoka9077]

@@MyOldSled I know the feeling. Glad you and your property didnt suffer too badly.

[@viktor7495]

I am going on a really long ride this weekend what should I bring

[@MyOldSled]

I did a couple of videos about things to carry. Overkill but can give you some ideas

[@Bobbyjwmwb]

Got much snow on up on the bruce? I suppose the trails are all closed due to covid now anyway.

[@MyOldSled]

Sadly no. We had a fair bit a couple of weeks ago, but it warmed up. Then we had a couple of cm last night, and you guessed it, it warmed up.....

[@joshshusta6418]

My buddy got zapped all the way up his arm Well I have a 97 ski-doo formula500 I have dim spark new plugs C.D.I replaced and coil it still won't fire up any idea's

[@MyOldSled]

Failing stator?

[@bigpoo02]

Need some help please, I have a 98 skidoo mxz 500. I changed the ignition coil and the cdi box. Still not getting spark, is there a why to test the stator? Thats what I was thinking it might be but not sure. Thanks hope you guys could help.

[@MyOldSled]

Hi BP. I would used the following, in this order, to diagnose no spark: 1. Verify spark plug condition. Plug could be defective, improperly set, worn-out, fouled. 2. Inspect spark plug cap 3. Check wiring harness and ignition cut-out (kill switch) switch - To test kill switch: Unplug kill switch connector from main harness then using an ohmmeter, connect test probes to BLACK/YELLOW and BLACK wires. Measure resistance, it must be an open circuit in its operating position and close to 0 ohm when depressed 4. Verify condition of ignition coil. 5. Check resistance of your stator with a multi-meter set to resistance: (WH with RD 49-75 OHM) (WH with BK/RD) 2.8 - .7 OHMS) Hope this helps

[@bigpoo02]

@@MyOldSled awesome thank you so much, I will do that tomorrow in that order :)

[@jonoze247]

Can i post a video responce to add to this video david ive been doing rookie and adance errors with this situation!!(vid response in the comments)

[@MyOldSled]

As long as you set something on fire....and no one got hurt. Or, there's a puppy.

[@jacksoncornish4051]

Can you please do a video on how to fix the kill switch on the 2005 600

[@MyOldSled]

Hmm...that's pretty specific. I'll think on it. Have you confirmed you have a problem with the kill switch?

[@jacksoncornish4051]

Ya

[@MyOldSled]

You should be able to buy just the switch part for around $30 or so. Just the red switch.

[@raymondburelle3425]

Get that feeling all the time especially when it could have been much more costly

[@MyOldSled]

Pretty common. I'm made much more costly mistakes.

[@PlouffeAlex]

Hi, i discovered your channel recently and it's some pretty good content. However, i have a question to ask you for my old sled. Its a 91 Ski-Doo Safari GLX 470 and i have a little problem with it. There's some prestone that flows on the engine but my prestone level don't drop...The flowing prestone is from my oil tank...? Do you have an idea of what could it be ?

[@MyOldSled]

Somethings leaking, but no way for me to know where it's leaking from. I'd say gat a cloth, wipe everything off as well as you can and go looking for your leak. Clean it off well and watch it while its running. The level must be dropping, just not enough to notice. Make sure you check the level when its cold.

[@jadenbuchanan8664]

Hey Dave, I recently bought my first snowmobile, a 1999 skidoo formula Z 670. Everything on it works just fine although it definitely does not like to idle even when warmed up and usually turns right off. Is this common or is there any way I could get it to idle?

[@MyOldSled]

Hi Jaden. Congratulations! I’d guess it’s the low speed jet on the carb is blocked. The low speed or pilot jet provides fuel at idle or low throttle positions. Take the carbs apart and clean them.

[@Racer57]

The only disadvantage I see with spark testers is if you have a bad spark plug you wouldn't necessarily know it because those testers just check the wire to the spark plug, not the plug itself.

[@MyOldSled]

Hi MSR. That's a good point, which is why I always start with fresh gas and a new spark plug first, as I mentioned in the video. They aren't perfect, they are a simple high level test.

[@kennytownes1979]

David will a coil work then stop on one cylinder give it little trottle then both cylinder fire again ?

[@MyOldSled]

What sled? I would say yes, and I think a bad stator would too.

[@kennytownes1979]

@@MyOldSled 99 mxz 600

[@kennytownes1979]

I order new coil probably should have taken off and tested it but too late now lol

[@MyOldSled]

Hey whats the worse that will happen, you'll have a spare. I'm just messing around figuring all this stuff out myself most of the time as well, but I recall stators will do that too. Let me know how you make out.

[@kennytownes1979]

@@MyOldSled hope not stator lol

[@kolehawkins3423]

hi dude love the vids

[@MyOldSled]

Hi Kole. Thanks man, that means a lot that you took the time to let me know.

[@kolehawkins3423]

@@MyOldSled yes i drive a ski doo 1996 500 and why does it always flood

[@MyOldSled]

So that sled has a primer right? Are you over priming? No more than 2 or 3 shots once you have fuel in the line. Thats common. Have you ever had the carbs apart to clean them.

[@kolehawkins3423]

@@MyOldSled no but that is what i will do thanks keep posting

[@marclapalme1394]

Where did you buy your tester? royal? Princess?

[@MyOldSled]

Hi Marc. I bought the inline one at Canadian Tire, and the other at my local parts store, Pinkertons. I don't think its a chain, but its a carquest dealer. Great team, super helpful. Both under $10.

[@marclapalme1394]

@@MyOldSled Thanks

[@Michaelhanley15]

Tip: if it is too bright out to see spark, put the plug on your tongue and try the test again.

[@MyOldSled]

There are a couple of other approaches I might try first.

[@steveartese9014]

It's a sure way to find out if you have spark and ignition 😂

[@MyOldSled]

Definitely effective. I had spark.

[@steveartese9014]

Hehe

[@nicholasconnelly3251]

Holy molly. Could have been bad!!

[@MyOldSled]

Yep. Amazing how fast it went up.

[@alkachow8171]

Sits here and mocks me😂

[@MyOldSled]

It's very subtle about it, but it does.

[@alkachow8171]

Great video! I recently got a skidoo legend 550f for my second sled it’s pretty nice!

[@MyOldSled]

Thank you Al. Have you had it out much?

[@alkachow8171]

I’ve had it out once this year. I bought it non running and cleaned the carburetor and made it run again. I live in maine but I rode it in the forks yesterday for the first time trailriding actually and it rides really nice! How are yours?

[@alkachow8171]

There was very little snow though lol lots of rocks right under the snow and lots of big trees down but it was very beautiful

[@yakbassing8588]

So the moral of the story is, Don’t be an idiot checking spark over friggin gas!

[@MyOldSled]

Close. Actually, the moral of the story is this is a really common test that a lot of people do every day, normally without issue - but because fuel vapour is heavier than air, it can accumulate in places that you aren't expecting and even though you've done it for years, if you're not careful, or lose focus for a second, it's easy for things to go wrong...Wait...Why does that sound familiar? Oh yeah...I think I mentioned some of that of that in the video.

[@juss-passin-thru]

I feel like such an idiot! No.....wait, I'm a guy. This feeling is normal. -_-

[@MyOldSled]

Dumb mistakes know no gender :)