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Discussion Starter · #1 · (Edited)
I have a 1999 MXZ 670 HO and it has started to bog and lose power frequently. It happens more when the engine is cold and does not stop until the engine and the engine compartment are nice and warm. When I release the throttle, I can't accelerate again until I let it return to an idle. As soon as the I let the sled return to an idle, I can grab a handful of throttle and it runs beautifullly until I let off, then I lose power until I slow down to an idle. It is also bad when going up a hill with a load like a sleigh.

I pulled apart the carbs and cleaned them thoroughly, but this did not help. Then I pulled apart the RAVE valves and cleaned them, no better. I checked the fuel filter in the tank, it was fine. I put on a new impulse line cause I thought maybe it was sucking air, not the problem either. I am no longer running the small basket filters on the carbs as per Bombardier's recommendation.

Can anyone help me out? Might it be the DPM? If so, how can I check this? Fuel pump seal maybe? I can't see the fuel pump itself being a problem cause their isn't a lot that can go wrong except seals. I'm at a loss.

Any help would be greatly appreciated.

Thanks,


C
 

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I am Spartacus
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The fuel pump has diaphragms in it that pump the fuel, they can get brittle, or tear. Then the fuel won't pump properly.
 

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CHECK THE CLUTCH

I have had a similar situation with a sled before and it ended up being the drive clutch. This is causing the engine to bog because the clutch is not shifting properly and it is giving you a higher than necessary gear ratio. I would check the rollers and the weights for smooth oreration.Just give the clutch a once over to eliminate that as a possibility
 

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Discussion Starter · #4 ·
Thanks for the post! I rebuilt the clutch last year and replaced the plastic clips and the sleave bushings. When it runs right, it runs like a top, and when it bogs, it is dead until it gets back down to an idle. I'm hoping that rebuilding the fuel pump will solve my problem. I'll post when I get it figured out. My last resort will be dropping in off a my dealer but I'm afraid of what the labor costs will be!
 

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Discussion Starter · #5 ·
Problem solved! I was replacing the heat shield on my exhaust because the riveted plates had vibrated to pieces and I found a quarter inch triangular hole where the exit pipe is welded to the exhaust pipe. I had it welded and voila, she runs like a top again!

C
 
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