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Discussion Starter · #1 ·
Had an interesting thing just happen on a little ride we did tonight.

I was following my son on a 250 Bravo for about 10 minutes, steady throttle posistion, around 5500 rpm when all of a sudden it almost shut down on me. I squeezed the throttle wide open and continued to feather it till picked up with a full power roar. I'm guessing this was a fouled plug.

Anyway continued along, this time constantly moving the throttle. More like full on to idle. Problem went away, for awhile. I thought I'd experiment, and sure enough if I kept a steday throttle around 5 to 6000 rpm, brrrrr,brrrrrr, brrrrr, and then it would pick up. However it almost shut down on me once, acting like it was out of gas. (My gas gauge broke the first day I owned it, so I can't tell you how much fuel is in the tank. Just know that I filled up about 40 miles ago.) Just when I was ready to pull off the trail it cleared itself out and I then just kept gunning the thing and it ran fine.

So, what I see here is if you keep a steady throttle in this zone, the plug(s) foul out. Keep changing the RPM and it works fine.

Anyone else seeing this problem?
 

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Discussion Starter · #3 ·
Yeah, the temp is indicating between the cold (bottom of the gauage) and 1/4. In other words at 1/8 of the range scale.

It sure seems weird, comes out of noware. This could be a real pain if you're trying to do some long trail riding with a group of slower riders.

Has it happened to you?
 

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no not me but,Bill Cudney had a thread going saying how he has seen inconsistent performance from the sled which he thinks is temp related as the engine moniters all the paramaters and adjust timing and other stuff which may cause bogging like the summits,when temps are low. Did you plug your decompressors,or is it stock.
 

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I have 300 miles on mine know, Have never fouled a plug.
Last weekend we were riding the side of the road, Just crusing
along, My sled started to foul a plug, I started pinning the throttle
and it cleaned up, Never happend again. I have the decompression
holes pluged.
 

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I'm not sure on this one but I read over in the summit section that the reason they run BR8ECS plugs as compared to machz BR9ECS is they need a hotter plug with the extra compression.Maybe this will help,but I'm no plug engineer
 

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Now that you mention it I had something like that happen last week, I went out for a little ride and it started to bog, I figured I was just runnng out of gas so I turned back to town but I still had a quarter tank left, I took it easy and made it back to town, but if I was actually runnning out I wouldn't have made it that far. I didn't see any warning lights or anything abnormal on the gauges.
 

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Discussion Starter · #10 ·
I'm still in the break in period, (150m) and I did not plug the decompression holes.

However, a auto machanic suggested I might have water in the gas, so I just put some iso. in it and will give it a rip.

Can someone explain to me what the symptoms of a fouled plug sound and feel like. Does it clear itself out or is the fouled plugged done?
 

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Same thing happened to me yesterday out on the trail, about 30 miles into the ride. I thought I was running out of gas.

I had 75mi on the tank, gauge was reading between 1/4 and E, on a trail, riding at easy trail speeds, and the engine just bogged, would pickup the rpm, then stumbled a bit then bogged again, ... did it 3 times....I thought I was running out of gas, especially after reading threads in Dootalk about the gas line tank pick up not sucking the tank dry..... anyway I rode kind of tentatively for the next 10 miles where I was able to buy gas..... Unfortunately they were sold out of premium so I only put $10 reg in to get me back home. If they had prem, I could have filled the tank and determined just how much fuel there was left in the tank.....I have gas line anti freeze in the gas as well, but it was fairly mild 0c or 32f....
My sled has ~650 miles and my last fouled plug was at 290 miles....
 

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Yup it's happened to me a couple of times, i have 17 hours on it so far, but still original plugs. Hold it at a steady speed for a period of time then give it some throttle and it hesitate for a bit and then takes off. If your on and off the throttle it run's smooth as silk.
 

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Discussion Starter · #13 ·
Went for the rip and guess what, died on the trail. The gas guage is broken, has been since I bought it, but the dealer is so far away I hav'nt bothered taking it back.

Anyway, otta gas, for f--k sakes. Don't let these things go below a 1/4 or you will have these symptoms. It started last night and put on a further 25-30 miles. Thought I was good to go and it started miss behaving right of the get go.

I was with my son on the Bravo, who laughingly took us both home for a jug of gas. Dumped that in and vrrrooom! Out of there.

It takes a little to get'er goin from a dry tank by the way. Just keep crankin E/S, and she'll eventually fire.
 

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goingmach_1 said:
Had an interesting thing just happen on a little ride we did tonight.

I was following my son on a 250 Bravo for about 10 minutes, steady throttle posistion, around 5500 rpm when all of a sudden it almost shut down on me. I squeezed the throttle wide open and continued to feather it till picked up with a full power roar. I'm guessing this was a fouled plug.

Anyway continued along, this time constantly moving the throttle. More like full on to idle. Problem went away, for awhile. I thought I'd experiment, and sure enough if I kept a steday throttle around 5 to 6000 rpm, brrrrr,brrrrrr, brrrrr, and then it would pick up. However it almost shut down on me once, acting like it was out of gas. (My gas gauge broke the first day I owned it, so I can't tell you how much fuel is in the tank. Just know that I filled up about 40 miles ago.) Just when I was ready to pull off the trail it cleared itself out and I then just kept gunning the thing and it ran fine.

So, what I see here is if you keep a steady throttle in this zone, the plug(s) foul out. Keep changing the RPM and it works fine.

Anyone else seeing this problem?
[snapback]261226[/snapback]​
See my post about the same problem. It is entitled "Possible new issue with 05 Mach?" I posted it there before I saw your post.
 

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I have almost 900 miles on mine and I had this slow speed plug fouling happen twice this past weekend where I was doing about 20 mph over a rough trail for a few miles. Once I was able to feather it out and the second time it fouled the pto plug. I have fouled 7 other plugs but always on cold start. Decompresser is not blocked. I will be switching over to the blend oil as BRP suggests to see if this cures the problem.
 

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There is an issue with the fuel outlet hose coming out of the fuel tank. At the front bottom of the fuel tank, you will notice a rubber fuel hose that has an "S" shape. This hose is sometimes pinched and prevents fuel from flowing freely. Look at yours if it is pinched. It is simply too long. Simple fix is to remove 1/2" from this hose and reinstall. This has solved the problem for many people who experienced the same symptoms.
 
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