91 EXT Special cutting out...HELP IM AT WITS END!!!!

[Hamerhead]

It starts and runs great, then bogs a few times and cuts out after a mile or two. Then it won't start. Let it sit for a bit (cool down?)and boom it fires and runs fine...until it cuts out again a half a mile down the trail...

I've isolated the handlebar switches with a jumper. Originally thought Throttle safety switch or Kill switch, maybe key switch? Tether is intact. I ran it today with 3 prong plug to bars pulled apart and jumped, same problem.

Sled runs strong an then just cuts out, like it's not getting spark. What would cause an intermittent spark condition like this? Cuts out when warmed up. Then starts happening more and more frequently.

Ignition coil?

CDI?

Stator?

I don't know how to isolate to trouble shoot this back. Any suggestions? Ideas or thoughts would be appreciated. I want to fix it without buying several different parts before I find it. Got the sled for my son and he's bummed at dad because he can't ride it...now I'm the bad guy!

Anyone out there have a suggestion?

[Vintagesleds.com]

[399jlo]

find your secondary ignition coils. Go for a ride until it dies. Pack snow around your coils and see if it fires back up. Happened to a friend's ElTigre'. That is how we got him home

[thepupstain]

Ive tried using a heat gun on the electrics in question while its on the stand in the shop..or if the parts are out and you have ohm specs, warm things up with the ohm meter connected and see what happens.

[Hamerhead]

Update:

I trimmed the plug wires back.
Replaced Plugs
Bypassed throttle safety switch and kill switch.

No Change, it still dies after about 5-10 mins then won't start for a few mins. Of note, when it starts after cutting out its throaty/almost boggy and will cut out if you give it throttle. Then it eventually comes alive and runs like a rocket.

Today when it stalled I packed snow around the external ignition coil. Didn't help, still took same ant of time before it started again.

I neglected to mention that the sled came with a key in the switch that wasn't the right one and it broke. When I pulled the key piece out I noticed the switch was all cracked, basically fell apart. I turned the switch on with a screw driver, so hopeful it was the switch...no change. I just got the new switch in the mail. I really don't think the switch is the culprit though.

Should I replace the ignition coil? They are only $32. Ive heard the CDI's almost NEVER go, so only other thing I can imagine is Stator or  some weird heat impacted gremlinI'll never find!

Why did I buy another Cat?

[hotdoo]

I'd change the key switch, my '89 Cougar has a problem with the switch,so I leave it on and use the kill button.hotdoo

[Hamerhead]

Tx Hotdoo,

I have the switch in hand so will do that next. I just have to figure out how to get to the back side of it...maybe take off the seat? I will update once I get the new switch in. I'm also going to double check all the grounds and  try the stator plug bypass.

If the ignition switch and tether are separate in the harness from the handle bar switches then I haven't been able to isolate them by bypassing the three prong plug on the steering column. I think thats just throttle safety and kill switch. Does anyone know how to do a check on either tether or key switch circuits? How about how to get to  them? They are low, down by the front foe the seat and the lower shroud is riveted on, I don't want to pull rivets If I can avoid.

Ah the joys of 25 yr old sleds and electrical gremlins...

Thanks for any ideas, appreciate your time and knowledge everyone.

[mikem4]

From your first post you said "it's like it is not getting spark". Has it been confirmed when it dies it has no spark? You never said for sure.

[Hamerhead]

I haven't actually checked at the time it dies, as its usually out on the trail. That's actually a good idea but it's sure acting like its suddenly losing spark. It runs absolutely perfect then one or two hesitations and bwaaaaaahhhhhhg dies. Will get it out in the field until it dies and then pop the plugs to check for spark.

Will update tomorrow after work.

Stay tuned...

[mikem4]

Bring a spark tester if possible or bring a brand new plug that you know fires to test with if possible. Quicker too. Then you can just pull the plug wire and use the tester or the new plug.

[Hamerhead]

Good one!

I do have some new plugs so thats a plan.

Thanks for the good idea.

[Earl]

my 2 cents, how about disconnecting the wiring harness and putting a jumper wire between the brown and black coming out of the stator, that would eliminate all wiring issues on the sled.  Then run it, if it craps out you know its the CDI or stator breaking down.

[Stigmen]

I have seen bad connections in the black plugs.  Will drive you batty.  I had 3 sleds of this era do this.  Now I seek out these sleds without spark.  Yours sounds a little different like a stator or coils.

[Hamerhead]

Update,

Got the boy out in the field today on the EXT after work. Sled started fine and ran strong and then died as usual after about 5-10 mins of running perfect. I ran over, pulled each plug and they both had spark. Popped plugs back in, unscrewed top of carbs and pulled float up on both, making sure everything was free. Tighten up and boom she runs. So now I'm thinking fuel pump or something in carb or fuel delivery somewhere. Boy goes round and round, thing's running great, maybe it is finally ok......BOOOOOOOOAAAAAAAHHHHHHG dies again. So I run over and check spark, NOTHING. No spark at all. Interesting side note, the Left plug was hot(almost too hot to handle, while the right plug was not as hot). Both looked grey/brown. That left plug was MUCH hotter than the right. Left facing forward.

Leave hood up, look at the stars a few minutes and then it tries to start, doesn't then after ten or so more pulls it fires again and I tell the boy to get it back in the garage before we have to push the old girl.

So now I know it's an intermittent spark issue wich occurs after its hot/good and warmed up.

Earl, I will try to do the jump at the engine plug, its the one thing I haven't done yet. How do I stop the motor in that case if it DOESNT bog out? Pull a plug cap?

I am thinking I bite the bucket and buy the $32 ignition coil. Or I REALLY bite the bullet and pay to have it fixed(horrors) I have a boy who is dying to ride his sled and every day that passes spring gets closer. I can't bear to see his face when he looks at me after it dies again...

Thanks for any thoughts.

[Hamerhead]

Stigman,

I suppose I should dig into that. How did you find the bad one, luck?

Too late, this thing has me batty already...

Interested in a nice 91 EXT Special? Runs great for 8 mins...

[Earl]

to kill the engine you need to pull the jumper wire off.