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Gas shooting from gas cap

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We went riding today and when my buddy cranked his 2011 up gas started shooting out of his gas cap hose for a few seconds..

The bike cranks up easy and runs great, dosnt fall off or anything BUT it's idling a little higher and getting hot faster and coming out of the overflow.. Any Thoughts?

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I appreciate the advise but it wasn't slap gas, it was pouring out of the line when it first cranked.. Like a steady stream.. somethin else is going on here.. Whatever's cause pressure to go back into the tank is the problem.. I'm not sure if it's a intake valve leaking possibly or a injector failure.. Or what. Besides idling high and running hot it's running strong as usual tho... Weird

Edited by Diggla117

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Anybody have any ideas before I go tearing this thing apart?

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Had he just re-fuelled, did he fill the tank to the top? Did it just act like a syringe when he sat down or something, pushing on the tank and compressing it so fuel over flowed?

Has it done it before, or since? Can you replicate the problem?

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Had he just re-fuelled, did he fill the tank to the top? Did it just act like a syringe when he sat down or something, pushing on the tank and compressing it so fuel over flowed?

Has it done it before, or since? Can you replicate the problem?

Nah we fueled up before we left town. Drove three hours then pulled the bikes off the truck and when he cranked it I saw the fuel run down the back of his front fender just a steady stream to the ground. That and The time before that when we rode it was constantly pushing fumes out of the cap. He kept asking if we were leaking fuel then I actually saw the fumes evaporating up. Then every time we wernt hauling ass it would start spewing coolant and idling high.... I was hoping somebody on here had something like this happen. I guess were gonna tear the bike apart Sunday. He said he wants to do the top end and I'm thinking that somehow one of the valves wasn't sealing and somehow pushing pressure back up the injector???? I can't come up with any other ideas. There is only one fuel line out the bottom of a 11 right? I figured I'd look into maybe trying to clean the injector if that's possible? Appreciate your help

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Also I appreciate the squeezing tank thought.. I'll check it This weekend when were working on it for flex. See it I can push on it and get it to spew

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Nah we fueled up before we left town. Drove three hours then pulled the bikes off the truck and when he cranked it I saw the fuel run down the back of his front fender just a steady stream to the ground. That and The time before that when we rode it was constantly pushing fumes out of the cap. He kept asking if we were leaking fuel then I actually saw the fumes evaporating up. Then every time we wernt hauling ass it would start spewing coolant and idling high.... I was hoping somebody on here had something like this happen. I guess were gonna tear the bike apart Sunday. He said he wants to do the top end and I'm thinking that somehow one of the valves wasn't sealing and somehow pushing pressure back up the injector???? I can't come up with any other ideas. There is only one fuel line out the bottom of a 11 right? I figured I'd look into maybe trying to clean the injector if that's possible? Appreciate your help

So that means you did just fill the bike's tank up. Before it was ridden. If the bike was in the sun on your 3hr drive, the fuel tank gets hot, heats up the fuel, the fuel expands, and exits the only place it can, through the cap's vent hose. When sitting in the sun with the bike off, the vapors expand even more than the fuel and escape through the cap.

As DHS stated, an overfull gas tank would spew out the cap if pressurized by the rider sitting on the seat! The front of the seat rides directly on the tank!!! Same with vapors and a half full hot tank, the vapors get rejected through the cap bent system. This is totally normal.

Pressure from the engine couldn't pressurize the injector and fuel tank so don't even bother to look for that. He could have a defective fuel cap. I would replace the fuel cap and hose, or at least clean it out internally.

Edited by Eddie8v

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So that means you did just fill the bike's tank up. Before it was ridden. If the bike was in the sun on your 3hr drive, the fuel tank gets hot, heats up the fuel, the fuel expands, and exits the only place it can, through the cap's vent hose. When sitting in the sun with the bike off, the vapors expand even more than the fuel and escape through the cap.

As DHS stated, an overfull gas tank would spew out the cap if pressurized by the rider sitting on the seat! The front of the seat rides directly on the tank!!! Same with vapors and a half full hot tank, the vapors get rejected through the cap bent system. This is totally normal.

Pressure from the engine couldn't pressurize the injector and fuel tank so don't even bother to look for that. He could have a defective fuel cap. I would replace the fuel cap and hose, or at least clean it out internally.

Yeah I'll try that. I guess we'll Findout Sunday. Maybe his tank does flex a lot. The dude has raced this bike a lot and def knows his shi and this seemed new to him.. And the vapors was coming from the tank when we were riding... Like the whole time we were riding he was getting high from it, or a headache. And nah they wernt baking in the sun. He kicked the bike and then it started spewing! Like all down the fender, onto the header. I was sketched out it was gonna go up in flames... Appreciate the input fellas, I'll get back to ya on this.

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Mine did it yesterday, hot day, bike cooked in the sun while getting geared up to ride. I had eth tank absolutely full to the top (over full) add the gas cap, let the fuel expand in the sun, and it has no where to go except out the overflow/breather. Just leave about an inch at the top to allow for expansion on hot days when you refuel.

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Update: so we tore the bike apart for a new top end (13.5 piston) and sent the ecu to Eddie to get remapped. Piston and ecu came in yesterday, we put it all together this morning and cranked it a few times letting it warm up then cool down completely then went riding this afternoon.

The idle went up by itself about half way through the ride and he said the only difference he noticed is the bike kept cutting off coming out of corners.... Were going to check the fuel filter tomorrow but other than that were at a loss. Also it sounded like the fuel might have been gurgling when we stopped for a break.. Thoughts?

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This happened to one of my bikes. Fueled up in town drove up 3500Ft extra elv. and couldn't figure out why gas kept dripping down my fender. Took a bit to realize the elv. was pushing it out the cap hose. Not sure if that's your issue, but hopefully.

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