Midrange Stumble around 5500 RPM

[sledheadd]

I have a very similar set up on the same year of sled with no problems.
My sled is ported with a 13.1 par head with dynoport pipe and y pipe.
I'm running 50/50 av and 91 from 4000' and up 100% av at lower elevations.

 

[Zone28M7]

I have a very similar set up on the same year of sled with no problems.
My sled is ported with a 13.1 par head with dynoport pipe and y pipe.
I'm running 50/50 av and 91 from 4000' and up 100% av at lower elevations.

See, this setup is supposed to be the SLP stage 5 setup, but it was built by a tech at Carls. It was his own personal sled. So a few things were different. No SLP head, it's a dragon head which is supposed to be higher compression than the Pro. It had stock reeds rather than vforce, carls did the port and polish, and they're running a reflashed ECU instead of a programmer. I run just straight 91. Maybe this thing should be running a 50/50 mix.

 

[nighthawk285]

Why don't you call Carls and talk to the tech that used to own it and pick his brain?

 

[Zone28M7]

Why don't you call Carls and talk to the tech that used to own it and pick his brain?

I have...for hours...he's at a loss

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[Zone28M7]

But I did find this in the clutch face...

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[Zone28M7]

UPDATE: Tested again today after changing out clutch face, installing thermostat and adding weight. ALL symptoms exactly the same. We actually tried shutting the sled down and pulling the plugs when stumble occurs. PTO side is good and MAG side is very lean. My immediate thoughts are injector or crank seal. And the crank seal looks fine. Thoughts anyone??

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[sledhead84404]

I just had to put all new fuel line from the pump to the pick ups in the tank thanks to the s..t fuel we can buy

 

[Zone28M7]

Replaced fuel rail and injectors. Issue still present. All I'm down to is coils, plug wires or ecu. Running out of patience

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[Always war]

I think sledhead84404 has the answer to your problem. I've seen this first hand, and the symptoms were the same as yours. Good luck!

 

[Rmk_RDR]

Find the problem?

 

[Zone28M7]

Nope. I've torn this sled to the ground twice. No idea. I've tested and/or replaced about everything on this sled. Tested TPS, fuel pump, injectors, ecu, plug wires and much more. Inspected motor top end, compression test, reeds, fuel lines, all wiring, clutches, throttle block, tss, etc. Replaced ecu, plug wires, coils, injectors. I'm at a total loss.

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[NapaMatt]

Have u tested fuel pump under load?

Mag side is the first on the rail...

Check stator wires too!! Dang inner ring eats wires!!!

What type of reeds do u have?

Stock or VF3?

 

[Zone28M7]

Have u tested fuel pump under load?

Mag side is the first on the rail...

Check stator wires too!! Dang inner ring eats wires!!!

What type of reeds do u have?

Stock or VF3?

How do you go about testing a fuel pump under load? Haven't checked stator yet. It's at the dealer now. Finally threw in the towel. Stock reeds. We inspected them first thing. They are in perfect shape

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[RJF]

^^^This. And the name is misleading, the SkiDoo thermostat is 28 bucks, the rest of the hoses and clamps and such add it up to right around 100 ish (depending on what clamps you go with, etc).

With the stock thermostat, mine had the same problem that I had read again and again about. Would run in the 120-135 range, then have a huge temperature swing when the sled was off. When I started it back up one day and it was at 170, that's the day I ordered the kit for the mod. Like I said......now once warmed up, I stay within a 15 degree range right around 110 all day.....pinned to the bars or feathering through the trees

And whats wrong with that? It's called heat soak. When you shut off the engine, the heat soaks further into the coolant bringing the coolant temp up. It doesn't hurt anything because the block is not actually getting any hotter than it already was. As soon as you start it, the stat opens, it gets a rush of cool coolant from the radiator, and the gauge drops like a rocket. This is very common and normal in many more things than just snowmobiles.

Maybe I'm missing something, but unless this skidon't thermostat actually helps cooling when the snow is bad or something, sounds like it's a waste of time/money.

 

[Reg2view]

FWIW, the $28 upgrade is always about keeping running temps below 130F, which keeps the ECU from slipping timing or overfueling.

Agree, temp spike means nothing, tho some have proposed the an immediately following cold coolant shock was causing piston failure if the motor was pinned after restart.

 

[RJF]

FWIW, the $28 upgrade is always about keeping running temps below 130F, which keeps the ECU from slipping timing or overfueling.

Agree, temp spike means nothing, tho some have proposed the an immediately following cold coolant shock was causing piston failure if the motor was pinned after restart.

Well, as far as running temps, a different thermostat shouldn't make a difference since the stock stat opens at 120-122* anyway, so either the snow is good enough and providing enough cooling from the exchanger, or it's not....

As far as pinning it after a restart, it should be common sense to not restart ANYTHING and pin it right away.

 

[bigchevrolet]

I am experiencing similar but much more drastic issues. Mine will not rev above 5500....Engine light comes on and stays on steady. Idle is fine and reverse works wonderfully but sled will barely move in forward. When running the dash diagnostic it display code 51-10. When you say test tps does that mean testing it or setting it and adjusting/check adjustments?

 

[nighthawk285]

And whats wrong with that? It's called heat soak. When you shut off the engine, the heat soaks further into the coolant bringing the coolant temp up. It doesn't hurt anything because the block is not actually getting any hotter than it already was. As soon as you start it, the stat opens, it gets a rush of cool coolant from the radiator, and the gauge drops like a rocket. This is very common and normal in many more things than just snowmobiles.

Maybe I'm missing something, but unless this skidon't thermostat actually helps cooling when the snow is bad or something, sounds like it's a waste of time/money.

It does help quite a bit when the snow isn't ideal. I wrote that wrong and was intending to put more emphasis on the fact that it stayed cooler, but the way I wrote it I added too much about the temp spike.

FWIW, the $28 upgrade is always about keeping running temps below 130F, which keeps the ECU from slipping timing or overfueling.

Agree, temp spike means nothing, tho some have proposed the an immediately following cold coolant shock was causing piston failure if the motor was pinned after restart.

^^^WHS

 

[Zone28M7]

I am experiencing similar but much more drastic issues. Mine will not rev above 5500....Engine light comes on and stays on steady. Idle is fine and reverse works wonderfully but sled will barely move in forward. When running the dash diagnostic it display code 51-10. When you say test tps does that mean testing it or setting it and adjusting/check adjustments?

By testing TPS I mean checking to see if the voltage is at .93 volts. It wasn't out of adjustment. We did not however check the base TPS voltage which is supposed to be .7 volts

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[Zone28M7]

UPDATE: Turns out I had a dead spot in my stator and the wiring harness to stator is partially melted. Haven't replaced yet but I gotta believe this is the issue.


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