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Discussion Starter · #41 ·
My experience over the weekend with the heat shielding was inconclusive. I started the ride with about a 3/4 tank of gas, and rode it pretty hard. I got it under 1/2 tank, and never had a problem, but...while we were at high elevation, the trail was relatively flat and the weather was cool. So while I never had a problem, I can't say for sure that the heat shielding was the causal factor.
 

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Discussion Starter · #42 ·
Maybe that product "Startron" that WUN likes might allow for more thorough combustion due to the effects of the ethanol in the gas which may reduce the chances of stalling. Makes all my engines start quicker and run smoother. So that might help at higher elevatioins. What do you think?

I like the sounds of it. I'll have to try a bottle.
 

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A friend of mine said he went with the next higher octane and startron and said it ran great.
 

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Just ran for four days here in Eureka(Silverton), just over 200 miles. Never under 10,000 feet and over passes at 13,000 feet. Neither 550 missed a beat!

Ran at 3/4 to 1/4 full on mine(the one that fails) and on the same trails that last year caused 4 or 5 failures. The only difference between last year and this year is maybe 10-15 degrees cooler this year and air filter cleaner than last year.

Maybe it took 5,000 miles to get broken in, haha.
 

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Just ran for four days here in Eureka(Silverton), just over 200 miles. Never under 10,000 feet and over passes at 13,000 feet. Neither 550 missed a beat!

Ran at 3/4 to 1/4 full on mine(the one that fails) and on the same trails that last year caused 4 or 5 failures. The only difference between last year and this year is maybe 10-15 degrees cooler this year and air filter cleaner than last year.

Maybe it took 5,000 miles to get broken in, haha.
Dav5942, My perception is the 10-15` cooler made all the difference. I live in AZ and have had 2 of the same experiences on my 11 700. Once at 6000 ft. and 90 Deg W/1/3 tank and once at 7500 Ft. and 75 Deg. W/1/3 tank. If I add fuel, I always carry some, it will start up and run fine. If I use non-ethanol fuel I don't have an issue, but it is hard to find. I beleive that what is happening is that once the tank gets blow 1/2 w/ higher altitudeand wamer temperatures the ethanol blend hits its vapor point. It may be doing it with more fuel in the tank also. but the head preasure on the fuel pump is high enough that it pushes the air fuel mixture into the pump, but at low fuel levels the pump can't suck it in. They need a pump whith more suction on more heat shielding for and ethanol fuel mix. Next year with 15% ethanol it is only going to get worse.
 

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Got my bike from the dealer and rode yesterday. I arrested with a half tank and rode it to almost empty. It never missed a beat. All of the riding was above 11000 feet and I did cruising between 20 to 40 and slow rock crawling. I think the pump fixed my issue. Temps were the same as when it stalled the first time
 

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just got back from colorado, have a thought about this. It might have been mentioned but i'm not for sure. The theme seams to be uphill, and less than half a tank of fuel. I noticed that on steep inclines the fuel gauge showed less than on a level surface and on a downhill grade it showed more. It could just be placement of the level indicator or could there also just be a design flaw or the tank. Could they be pulling fuel from a position that doesn't allow it to access all the fuel when on an incline like the gauge shows? just a thought
 

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Could they be pulling fuel from a position that doesn't allow it to access all the fuel when on an incline like the gauge shows? just a thought
:rocker:If the location of the fuel pick up was the problem everyone would be having trouble at high altitudes and on inclines and many have no problems at all. All tanks with float type fuel guages can give false readings on an incline.
 

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:rocker:If the location of the fuel pick up was the problem everyone would be having trouble at high altitudes and on inclines and many have no problems at all. All tanks with float type fuel guages can give false readings on an incline.
I agree. I didn't really say it very well, i was still pretty tired from the drive back. What i meant was that if it only did it on a low fuel level in the tank. But if some aren't having the problem on low fuel level then you'd be right of course. Not for sure just a thought.
 

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I agree. I didn't really say it very well, i was still pretty tired from the drive back. What i meant was that if it only did it on a low fuel level in the tank. But if some aren't having the problem on low fuel level then you'd be right of course. Not for sure just a thought.
Went thru the same thoughts last year, but since my wife's 550 did not fail thought maybe something was restricting flow in my tank only. But-----now not failing---maybe----so far?
 

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:rocker:To anyone concerned, my friend Nate (09 700) has recently told me that since our trip to Taylor Park Co in Aug. where he had issues with plug fouling, stalling, and poor performance, he has seen a huge improvement at high elevations by switching to 87 octane fuel (from 85 octane) and using StarTron fuel stabilizer. He states no more problems!

Worth a try for anyone having high altitude issues!:lala:
Turning on the key and letting the pod/ECU fully initalize (wait till you hear the fuel pump stop running)before hitting the start buttom may help too!
 

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Hey Guys,
I havent been on in a very long time. Hope everyone is doing well. Im bumping this thread. I just got back from another trip to Silverton, Co. My new fuel pump the dealer installed didnt fix the problem. The first ride that the grizz got down under a half tank it started dying out agian while climbing back up the pass. I unpluged the vent valve to see if that made a difference. It didnt. I opened the gas cap. Still died. Im stumped. If its over a half tank I never have a problem. At or under a half tank and climing it will spit and sputer and then die. let it sit a few minutes and it will start and you can go another half mile. Then dies again. I need help guys. Its very frusterating watch my pops on a popo with no problems and my sister on a canned ham with no problems. HELP!!!!! PLEASE!!!!!!
 

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To be quite honest I didn't read all of the posts on this issue, but I'm convinced that a good majority of the fuel issues could be avoided by using some kind of fuel stabilizer. If it were my bike I would dump some seafoam in the tank and run it for a while, It might not clear up right away, but it just might work. I see alot of friends with problems with everything from quads to snowblowers, who don't use stabilizer. I use Sta bil marine grade in EVERY tank and have zero issues with any of my toys. After all they were designed to run on gas, not moonshine, that is alot like methanol. Anything thats not driven daily needs something to keep this stuff from breaking down in the tank or gas can. IMHO. Hope you soon figure it out.
 

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I think its something more than that. the first time it happened I had only had the atv for three months. Its not a fuel quality issue. It runs fine when full. Runs fine when going down hill also. its something else
 

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I seen one guy on here with that and he switched to 89 octane with startron and it went away. I'd syphon all the 87 out try a whole fresh tank of 89 octane.
 

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It may not be the fuel in the tank, but what the methanol did to the fuel system. At this point I would cover all of my bases.
 

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First time it happened I was running 89. Dealer said run lower octane at high altitude. This time i was running 87.
 

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Another year WITHOUT a failure(previously many failures over 5000 miles), now 7000 miles! The only thing we did was put in a NEW air filter element.
 

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I still don't think it's a fuel quality issue either. I think it's a fuel delivery problem. Is it not picking it up or not venting pressures properly?
Though aren't we supposed to run 91 octane in these??
 

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Discussion Starter · #60 ·
Since applying the heat shield (as seen previously in this thread) to the underside of my gas tank last fall, I have only had my Grizzly up above 10,000 feet one time. However, I purposely ran it down to the point that the auxiliary light was flashing, and it never missed a beat. I'm not prepared to say mine is cured, but so far so good.
 
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