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Discussion Starter · #1 ·
Hey guys and gals,

On my 03 summit 700 i have been experiencing poor fuel consumption just recently. Compression is good, I have went through the carbs, its running well.

Pilot jets are 17.5, mains are 500. Fuel screw turned out 2.5 turns. Plugs burning good.

I took the sled for a ride out yesterday and i had burned through 3/4 of a tank in 40 miles/65 kms.

So I came home, yanked the carbs and recleaned them, all was good there, checked for sticky brakes, any bearings that were shot, regreased everything, filled up, and same thing sled ran really well, but is using fuel like a pig.

Last year it was getting considerably better mileage. Not quite but almost double.

Im not really sure where to start looking since I have tested for compression and the carbs all ready.

Any help appreciated.
 

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When altitude compensators go bad, they run rich. Might be a place to start. Sorry, I don't know much about the 03's way of doing it. (DPM?)
 

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its 13 years old might be time for some new ones does it have new plugs also? I just got some new ngk br9eyas for my 90 formula plus 521 we'll see how she does. dropping the needle or "clip" 1 notch i would'nt think would doo much I usually put my clips in #3 and take a short ride and check plugs they will tell you whats going on.
 

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To clarify, the needle and seats we're talking about is the float. If it is leaking while turned off, the fuel is seeping through the needle valve inside the float bowl.

Fuel consumption is a different matter, I would point that back to altitude compensation issue. 03 will have that plastic thing (pressure manifold) that the hose-nipples break off all the time. Make sure none of those are broken. If they are, then just get new plastic nipples from a hardware/plumbing store, drill and glue them in place.

If you're like me, the whole time you're working on it you'll be cursing BRP for making such a weak link. (i've had to do two of them on friends machines).
 

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Ok so just wanted to update on what Ive done so far.

I was chasing a hanging idle so i swapped the pilots to 20s. I have taken the carbs apart and I have replaced the o-rings in the fuel bowls.

IMG_4897_zpsn6iwphgv.jpg
Ok so they were replaced wrong at some point in time.

I turned the fuel screws back half a turn (this wont help my mileage i know but Im just stating all Ive done) I also put the needles back in the center where they were. I readjusted the oil pump so its spot on, and it doesnt hang up at all, choke cable doesnt hang up and I readjusted both the choke and the throttle cable when I hooked it all back up, but I do that each time I take the carbs out, carbs are synced perfectly. I put my sled up off of the ground and checked bearings, checked track tension, everything is smooth and working good.
I didnt take the clutchs apart, but I blew them out and cleaned the faces of them on both the primary and secondary.
The only other thing I can think of that is different than last year is i put on a aftermarket fuel cap, due to the stock one having a cracked lens.

I rechecked the compression, and its 145psi on both cyclinders testing it cold. This should mean that the rings are still good right?

yesterday I hooked up our skimo cutter and took the kids for a ride, and it seems a tad better, but really not much different. Plugs look a bit rich though, but I was puttering much slower yesterday as well.

IMG_2469_zpsljjx2up5.jpg

So Im thinking about the last thing to do is delete the dpm, it MUST be having some sort of issue, cause I just cant think of anything else it could be at this point. The one other thing I havent done is changed the main jets or those needles.

Ive deleted the round slide hac/dpm system on my old summit but I can see this flat slide is a little different, so ill have to look into it a little what to run for jetting and whatnot, and which hoses to plug and leave open. (unless someone may know offhand!)

Any other thoughts? Anything i am missing?
 

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I think your chasing down the wrong trail, literally. What have the riding conditions been like? Where are you riding? Is it wet, heavy snow or light fluffy snow? Did you slack the track for summer storage and it's tighter this year than last year. Mountain sleds and mountain riding is very condition specific. If this is only your second year with it or first year with vastly different snow conditions I bet your riding it harder than before and not realizing it. You might also have become more comfortable on the machine so your pushing yourself more. If it was so pig rich that you had wet plugs, flooding and stalling or poor throttle response then I would say something might be wrong but if it's runs good and the power hasn't fallen off I would say it's one of the above.
 

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Riding conditions, style, and aggressiveness havent changed.The only thing that has changed so far is the fuel consumption.

We had a baby last summer so the wife didnt snowmobile much the previous winter, and she hasnt been this winter much either, so ive really been sledding just by myself. I do ride with my parents every now and then and they are in their early 60s and ride very tame, and ive been mimicking that style, as well as ive been riding and checking how I normally ride. Ive had the sled for a few years now, and have been riding for 30 years, ever since I was 6 years old, it doesnt take me long at all to get comfortable to a machine.

SOMETHING is up with the machine somewhere. Its simply using more fuel, least by the gauge and the odometer. Im pretty conscience on watching this sort of thing because i do a fair bit of riding by myself in my local area.

Although I do get what youre saying Tug driver, and i do agree with you in the sense that the sled is running really well, and the plugs dont tell a story of something being wrong. I guess one way of looking at it, is i am going through the sled and fuel system with a fine tooth comb, and thats never a bad thing.

Its just way different fuel consumption than last winter, and not for the better.
 

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Delete the HAC. If it doesnt make any difference hook it back up. Certainly worth trying. The delete has fixed many a Skidoo on this forum- Including my '99 Summit X.
 

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Discussion Starter · #12 ·
Yes slayer, I have deleted my old summit as well, i believe from your instructions, and i took a bunch of pictures of the process! It did make that old summit hum along pretty nice. Im hoping that fixes this one! We bought the wife a 2011 gsx 1200, and our sled budget is eaten up this year from that sled, so I gotta try my best to get this one working well again.
 

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Fuel lines leaking?
Fuel pump maybe?
Can't imagine it running good if that much fuel is pouring through the engine.
 

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Fuel lines leaking?
Fuel pump maybe?
Can't imagine it running good if that much fuel is pouring through the engine.
X2! I would have to think it would be bleeding fuel somewhere externally or so flooding rich it would barely run. And be far from rideable.
 

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Discussion Starter · #15 ·
Since Ive put the needles back, it tends to run a tad rich, but not THAT bad, least not from the tales the plugs tell. I didnt do anything with the fuel pump yet although I may have to, and no leaks that I can see or smell. Like in the garage I can idle it or run it for a few minutes, and it doesnt show a leak anywhere.

That was my original first thought as well though, and actually the very first thing I did check.
 

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Discussion Starter · #16 ·
Ok so I deleted the dpm today and took it for a ride down the river where I live. No change. I checked the plugs and the one side was running lean. (any idea why this would be? I plugged the lines the same, vented the lines the same on both carbs)
The sled was also running a little poor with the dpm deleted. Holding the throttle at around mid range, and it was almost sputtering, and the top end was weaker. I switched out the plugs to a brand new pair of br9eay that I had in the sled, took off and no difference.

So I switched plugs and rode over to my fathers house, hooked the dpm back up, and took off again. With the dpm hooked back up the sled was a beast again. It ran really hard, really strong, back on the river it pulled really hard up to 80 mph. Most of the riding was done at about 1/3 throttle though, for the whole test with the exception of a couple times when i opened it up to see how it would do at higher rpms.

Im not sure what to think, i checked out the mileage and its around 7-7.5, which is better than the 6 when I first started, but its still not great, and no where near as good as it was last year!

My father rides a 01 or 02 grand touring 700 and his gets really good fuel mileage, and I think the next step is to go for a ride with him, us both fill the tank, and see how much worse mine is. Mine was always a little worse than his, which I assume is from the track difference and gear difference, but they were too far off when we used to go on rides.

Im thinking next step for work is a fuel pump kit, maybe replace the main jets with new ones, the needles and floats seem good, not sure if its worth it to replace all of that?
 

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Discussion Starter · #18 ·
Well last year I was using it out of a bulk tank, this year is out of a different bulk tank.

I could try running premium, but I didnt run it last year at all I dont think.
 

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old ski-dool
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Do we really ride to be conservative? That's a big NO.....
If your sled is running good, then just go out and have fun. Fill the tank when it's empty and have some more fun.
Your over thinking it my friend.
 

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Discussion Starter · #20 ·
Yeah you may be right about overthinking it, but it does bug me that its different fuel useage from last year, with no reason! I feel like I want to fix it, but how do you fix something thats working so well?!
 
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