Brought the R* in today because of the gas pukeing out the air box. Now that several people have complained and Yamaha has recognized the problem they have agreed to take a good look into it. I think it's going to be the fuel pump. The mechanic has agreed to replace it if he can't find anything else wrong. I know several others here have mentioned their bikes have this problem so I will keep you posted on results. Could be a week or so if he has to order a new pump.

If your float and needle are set and working right the fuel pump shouldn't cause that IMO.

The only constant when it does this is the fuel pump doesn't shut down. It pumps like crazy until the engine finally starts and fuel flows. I have changed the float setting and cleaned out the carb. The problem is you can't induce this, it just happens when it wants. We were thinking the back pressure sensor on the fuel pump has an intermitant problem.

hey i had a similar problem with my bike, never did find out why but after i started turning off the pet cock the problem with puking after the bike was hot and gas going into my crankcase and raising the oil level over night went away
i always wondered if it could be a gravity problem,leaving the gas on and it leaking into the carb and over filling it

Thebru,
I am anxious to see what the answer is. My scoot started doing this on hot summer days after I got about 2,000 miles on the bike. Only when it was really hot. I changed pipes, BAK, AIS off, jetted, checked floats and carb when I had it off for jetting. All was OK. I went another couple thousand without a problem and now intermitently I get puking and continuous pump operation. My guess is that the floats are sticking for some reason, probably pressure from the heat. It never happens on a cold engine. I have not had it back to the dealer, at least not the one where I purchased it. We had a falling out when the scoot was new when for CYA reasons I was going to have the first service done there. I called for an appointment as was told they could get me in about 3 weeks. I said so I have to park the bike to wait for this appointment??? They said well you can come in and hope we can fit you in. Needless to say I did my own service and my scoot has not seen a shop since. I have found a better dealer, I think but would like to get this issue cleared up. Nothing like lots of raw gas flowing down on scorching hot exhaust pipes to get your attention

The shop called today. They are going with a new fuel pump. It's the next logical thing to try. They agreed with me that whatever sensor in the pump that detects back pressure isn't working right, and at this point with others coming in with the same problem, they are going to start throwing parts at it till they find the problem. We'll know soon...

Try some PEPTO BISMOL in the tank!

...Sorry guys! I saw the heading, "Carb Pukeing" and had to look,
and I just couldn't resist adding some humor!

I hope your carb gets feeling better soon!

Hey Bros. What year are your bikes? They look like 04's like I got. First I've heard of this issue. Good luck with the fix.

05'.

2005. No problems yet. (touch wood)