Kinda sounds like why ships sink in the Bermuda triangle.

Musky wrote:
Kinda sounds like why ships sink in the Bermuda triangle.
Oh GOSH! Hope I wasn't THAT scientific!

You hit on part of my theory. The pump is holding pressure so it keeps feeding the bowl. But it also keeps the bowl presurized too. I'm thinking with out the pump there would be no pressure and the gas would bubble but wouldn't flow out. Boiling water in a kettle with a lid on (pressure) boils out all over the place but take the lid off (no pressure) and it just bubbles without overflowing. That's why other ships don't sink.

Musky wrote:
You hit on part of my theory. The pump is holding pressure so it keeps feeding the bowl. But it also keeps the bowl presurized too. I'm thinking with out the pump there would be no pressure and the gas would bubble but wouldn't flow out. Boiling water in a kettle with a lid on (pressure) boils out all over the place but take the lid off (no pressure) and it just bubbles without overflowing. That's why other ships don't sink.
Gasoline has a very high boiling point when under pressure (pump to needle valve)
that's why YAMAHA has that part of the fuel system pressurized. (old gravity-fed carbs were prone to "vapor-lock."
Carburetor float-bowls are NOT pressurized, they are at atmospheric pressure. The carb couldn't work correctly if the float bowl were pressurized. Carburetors operate on a venturi-vacuum effect. (No pressure involved except for the accelerator-jet pump.)

Boiling water in a kettle with a lid on bubbles water all over, because the kettle's too full.
Boiling gas in a float bowl bubbles gas out all over, because the float-bowl's too full.

Heating water in a SEALED kettle causes great pressure. If pressure in the kettle remains high enough, the water can be heated to hundreds of degrees above the "atmospheric boiling piont" (212 F), and the water will not actually "boil" under pressure.

Open this extremely hot vessel wide open to release the internal pressure and the water will instantaneously flash to vapour, expanding to several hundred times it's liquid volume!
BLAAMM!!!!
...Your'e not around anymore! Youv'e just been blown up! (A Steam-Bomb.)

Just givin' ya some reading material to pass the time Musky! <br><br>Post edited by: StarMyram, at: 2007/03/29 21:53

Take the lid off the kettle and it stops boiling over. Same amount of water.
The fuel pump does fill the bowl by pressure. Otherwise it wouldn't be a &quot;pump&quot;. The pump sends gas down line until the bowl is full and the float closes the needle. Then the pump holds that pressure because there is no release in the closed system. If there was no pump there wouldn't be the pressure feed of gas to add to the problem. I think if the pump had some kind of electronic one way vent that opens on shut down instead of boil over we would have pressure release. Kinda of like not having a pump. Hense the question on pumpless. But like I said it's all just a shot in the dark theory.

I'm enjoying this discussion Need more people in it though.

Happy to join the fray...problem is, everything everyone has said makes sense, so I have no point to argue...dammit. I am by no means an expert or a wrench, but I do love methodical logic in problem solving...do it with computers all the time. Please, someone tell me if I'm way off, but this is my take on it...

The reason the fuel pump pumps is because it detects a drop in pressure in the gas line, correct? This happens when the gas level in the float bowl is lowered...lowered pressure detected, pumps pumps to compensate, just like an air compressor keeping the tank at 100 PSI or whatever level it's supposed to be. If there's a faulty sensor in the pump (ala Bru), the fuel pump keeps pumping to compensate for the fuel it &quot;thinks&quot; isn't there. Buildup in pressure, and the gas has to go somewhere...out the carb and onto our legs? And a hot carb that boils gas just expedites the expulsion process.

It's either that...or gremlins.

RK

Hi Guys

I have been reading your debate on the gas puking issues

I have a 05 R* and today had multiple problems for the first time

I first notice a kinda quick slaping sound at certain RPMS like maybe a loose exhaust pipe bracket letting some escape before hits muffler or a slight continuios back fire in the pipes

than I stopped for a while to make a cell call and the bike smelled of gas and wouldn't start also seemed hotter than normal

The days temp was around 62 F and had about a 45 minute ride

it finally started

than I stoped again to get gas and it sat for maybe 15 mins and wouldn't start i am applying no throttle just pressing start which is how it always starts for me

I than notice a puddle of gas under my bike this happened 4 times it was like a water fall and one time it was all over my foot. it would start run for to secs
puke and stall.

I tapped on the carb with a wrench in a couple of places and than it started and I made it home , bike seemed extremly hot for a cool day

any thoughts or comments would be great or is this something I need to get used to

Thanks Guys

Arcturus

Your talking about a LOT of gas when this happens that stops immediatly when the bike starts and the pump stops, way more than what's in the bowl. If I turn the key off it stops because the pump stops.I have never had this happen on any other bike, and I have ridden in some very hot places(Death Valley!!). If it wasn't for the warrenty I would seriously consider changing it to gravity feed(as per tech tips). Of course if this works I'm back to being happy scooter trash and will leave it alone till the pump finally fails.
However, to get back on the pumpless point, I can't see this happening with a simple gravity feed system, at least in my case. The carb never pukes on it's own. Only when I turn the key on and the pump comes on(and doesn't stop) does it puke. Without the extreme pressure of a faulty pump it doesn't happen, or when the pump works right. There is a direct correlation here that was never present with gravity feed.

Hey guys, do what you want but I can tell you I will not go without my fuel pump again. I loved the idea of ditching the pump so I did. Took me a few months to find the larger needle valve. Changed it and ripped the pump off and pulled the vents out of the cap and threw it all in the Box-O-Parts. Took it for a few rides loved it. Road with my brother and turned into drag race. Allways fun! Problem was I would run the carb out of gas in 3rd gear. Realy sucks!! Also had it do it riding 2 up on a long uphill grade. Cleaned everything and checked float level everything was perfect. It did it again so i said chuck it farle and put the fuel pump under the side cover and stock needle valve in. No problems running WFO. Have never had the puking problem. So I recomend staying with the pump.

It will get worm enough to ride in central pa. But I still can't ride I need to babysit the munchkin. And the wife doesn't approve of putting him in the saddle bag.

Chris

Harley Hunter wrote:
But I still can't ride I need to babysit the munchkin. And the wife doesn't approve of putting him in the saddle bag.

Chris

Drill a couple vent holes for air, he'll be okay. Remember when you were a kid and caught bugs and put em in a jar? Couple vent holes in the lid and they were good to go.