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900 still not working

I just finished replacing a piston/cylinder in my 2005 900 fusion because it appears that I got a scuffed piston due a lean condition. Prior to the scuffed pistion, I was having idle problems (started at the same time that the piston got scuffed when I blew a belt at about 3/4 throttle) and attributed them to the piston/cylinder.

Well, I still have the idle problems...when I first start the sled it will barely idle and usually stall (this happens for the first couple of times). Then the sled starts and has a high idle (usually around 2700 RPM).

I will check my TPS tomorrow after I get a new regulator (as the one I have now is not within tolerance) [Thanks to mountainhorse for the how to build your own TPS tutorial].

Any one have any thoughts on what could be wrong if it's not the TPS? I'm dying to get out as there are only a few weekends left!

Thanks in advance.
 
Sounds like you may have an air leak, a leak-down test might be a good idea before you run it anymore. I don't suppose you changed your crank seals when you rebuilt the top end? Intake boots in good shape?
That said.... bad or out of spec TPS's do some strange things, I'm just not sure if they will cause a lean condition.
Good luck and let us know what you find
Dan
 
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What's a leak down test and can I do it myself? I had the engine out and was able to look closely at the crank seal and everything looks great. The only thing I didn't look at would be any seals around the PTO as I didn't take the primary clutch off.
 
What are your thoughts on the crank turning a little? just enough to put the timing out? When the belt blew a piece of the belt went down in behind the primary, wrapped around the primary and secondary. When it did this it stopped the engine and locked up the track before the sled was stopped. It was a real PITA to get the belt out at 3am in the morning.

I don't see any problems with the crank. There is no slack. everything is nice and tight. But what if the belt wrapping around caused it to turn just slightly?

How likely/possible is that and could that cause the symptons that I'm seeing?
 
Not very likely! It is more likely that u put a hole in the pto side crank seal. when the sled is running spray a little carb clean behind the clutch onto the seal and see if u notice any difference in the running of the engine. if the idle goes up when u spray around there then u have an air leak and ur seals need to be changed.
 
thanks chunky...I'll try that. If that's the case, can I split the case, apply the crank case bond and put it back together without changing out the other seals on the crank?

Also, I've been reading my manual and it appears that it is very possible that the crank indexing is out! It says that this can happen due to:
- Hydraulock from water or fuel
- Impact to drive clutch from foreign object or accident
- Abrupt piston or other mechanical failure
and what happened to me....
- Engine lock-up due to drive belt failure
 
I'd bet it's that PTO crank seal. If you split the cases then you only need to change the outer PTO and should change the outer mag end seals. Make sure you check the crank runout while you have it open.
If the PTO seal was damaged by the belt failure it will definately cause the lean burndown. TPS check is important and worth the effort as well.
Crank indexing issue is possible of course but less likely than the others in my opinion.
Good luck with your repairs!
 
The thing I'm still stuck trying to figure out is how could the belt blowing be causing the result of this, the troubled cylinder/piston are on the Mag side as noted in his thread earlier, not the Pto side? How could the PTO crank seal going out cause the Mag side to score?

The leak down test would be a good easy check tho to tell for sure if the pto seal is out.
 
so I'll have to see if I can find a leakdown tester. I'm going to see if I can find a regulator and build the TPS tester to check that TPS is ok first.

I'm starting to lean towards some kind of electrical problem. The only problem is the idle and low end power bog. Other than that the sled seems to work great. When I get the sled moving everything is good...very responsive like nothing is wrong. This was the case before I rebuilt the top end as well. I did experience some strange electrical issues around the same time...lights other than the brake light coming on when I put the break on, my gauge would automatically switch from speedo to rpm digital read out and back. The "up selection" seemed to be locked out at some points but down always worked....The reverse light would come on dim when I put the high beam and then fade out and go away. I attributed this to the warm, mild, wet conditions and didn't have dielectric paste available to put on all the connections but I've since acquired it and plan to coat all connections.
 
The thing I'm still stuck trying to figure out is how could the belt blowing be causing the result of this, the troubled cylinder/piston are on the Mag side as noted in his thread earlier, not the Pto side? How could the PTO crank seal going out cause the Mag side to score?

The leak down test would be a good easy check tho to tell for sure if the pto seal is out.

Yeah that would be puzzling! I didnt see it posted that it was the MAG side. I just assumed it was the PTO side considering it was mentioned that he wrapped a belt around both clutches.

how did we go from having an engine problem to and electrical issue?:face-icon-small-dis
 
Ether ---

Spray it around it will find the leaks.
USE EXTREEME CAUTION WITH EITHER! CARB CLEAN IS WAY SAFER!
EITHER CAN IGNITE WITH JUST A FAULTY SPARK PLUG WIRE AND BOOM!!!!!!! I'M NOT TRIIN' TO BE "MR. SAFETY"....I PERSONALLY HAVE HAD FIRST HAND EXPERIENCE WITH EITHER (AS A OBSERVER) CARB CLEAN WILL DO THE SAME AND MUCH SAFER, ONCE YOU FIND A SPOT THAT SEEMS TO BE A BAD AREA, THEN GIVE A SMALL SHOT OF EITHER TO SEE IF RPMS GO UP, CARB CLEAN RPMS WILL GO DOWN.
FUMES FROM EITHER ARE WAAAAY MORE IGNITABLE THAN GAS IT SELF!
 
I just dropped it off at the dealer. They will have a look at it tomorrow. Hopefully, they will find something.

I did spray WD40 around the PTO seal and no change. I checked the TPS and it's spot on.

I didn't have time to make/find a leak down tester so I haven't done that test yet...although it sounds like the cats meow for finding any leaks.

The thought on electrical issues is just the fact that I'm grasping at things...the sled seems to be running great other than the idle/low-end bog.

I have heard that fuel problems (stuck/clogged injector, etc...) will cause a lean condition. Can someone explain this to me as it doesn't seem to make sense...The oil and fuel systems are linked but separate; if I'm not getting enough fuel then shouldn't there be excessive oil (meaning that you would have a rich condition)?

This has been a somewhat expensive year so far....1st a fuel rail, then the piston/cylinder, o-rings and gaskets, and I took the opportunity to change the exhaust gaskets/exhaust valve gaskets and clean the exhaust valves (they were in great shape considering I've put 2000+ km on the sled this year).
 
I just dropped it off at the dealer. They will have a look at it tomorrow. Hopefully, they will find something.

I did spray WD40 around the PTO seal and no change. I checked the TPS and it's spot on.

I didn't have time to make/find a leak down tester so I haven't done that test yet...although it sounds like the cats meow for finding any leaks.

The thought on electrical issues is just the fact that I'm grasping at things...the sled seems to be running great other than the idle/low-end bog.

I have heard that fuel problems (stuck/clogged injector, etc...) will cause a lean condition. Can someone explain this to me as it doesn't seem to make sense...The oil and fuel systems are linked but separate; if I'm not getting enough fuel then shouldn't there be excessive oil (meaning that you would have a rich condition)?

This has been a somewhat expensive year so far....1st a fuel rail, then the piston/cylinder, o-rings and gaskets, and I took the opportunity to change the exhaust gaskets/exhaust valve gaskets and clean the exhaust valves (they were in great shape considering I've put 2000+ km on the sled this year).

Being lean on oil and fuel are 2 different things. the lean fuel condition is caused by not enough fuel entering the combustion chamber to make the optimum ratio of about 14:1 air to fuel. when ur injectors r working properly they r spraying so much fuel for so much air entering the cylinder, when u remove some of that fuel the ratio goes up because u r still pulling the same amount of air into the system. hope this makes sense. lol
 
The other results sound like a pinched/burned harness around the engine. Did you remove the fuel tank? Have seen wiring get tight around the front of it around the chassis...?
 
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