bike starving for fuel 99 valkyrie

[Kevin p]

Any ideas my bike works great around town  on drives runs out of fuel figured out today when i open gas cap it start right up good for another 10 min.Going to take tank off tomorrow is there something that controls how air gets in tank.  Bike ran good before stored. Any ideas would be great  thanks

[ptgb]

Sounds like a kinked or blocked vent line.

Run it and after it starts to die or dies, use your second key to open the gas cap. If you hear a "whoosh", the vent is not working correctly.

The vent line is the small rubber line behind (towards the seat) the petcock.

[Kevin p]

Not hearing any noise bike works great around town never know anything was wrong.Been doing a lot of reading. I thought gas was gravity fed.

[ptgb]

It is gravity fed. What happens is if air is not getting into the tank to displace the fluid that is leaving it, it will create a vacuum effect, keeping the fluid (fuel) in the tank.

I'll bet you $2.50 that the line is partially kinked. That is why it runs good around town and starves for fuel at higher speeds.

Before you take the tank off, get a zip tie and place it on the edge of the fuel filler. Close the cap on top of the zip tie too allow a small gap for air to get in. Bet it will run fine in all riding scenarios.

[8Track]

Yes - almost certainly a kinked vent line. You are getting a vaccuum built up inside the tank which is stronger than the force of gravity. By opening the cap you are releasing the vaccuum. Bike will run fine until it builds up again.

Another thing to check is the vaccuum line running from the petcock to the #6 intake runner. If this is cracked then there won't be enough vaccuum to reliably hold the diaphragm inside the petcock open. This issue tends to show up as fuel starvation at higher rpms.

Cheers,

Mark

[Kevin p]

Fogged the carburetors in the fall must have kinked the vent putting tank back on.Caused me allot of grief broke down trailered it home had no spark.Ran the battery low when i was trying to get it off the road,got reading in the form someone posted need allot of juice for spark was after cleaning all the wires couldn't figure it out.Charged the battery got spark,that's when i figured gas problem,Checked carburetors had fuel was stumped.Opened gas cap to pull some fuel out to put in plug hole bike fired up,air locked,Was worried something in the petcock was causing the problem.Easy fix going to be a nice weekend here for a ride.Thanks for the replies,help.Not hard to act stupid sometimes.Cheers   

[HayHauler]

Fogged the carburetors in the fall must have kinked the vent putting tank back on.Caused me allot of grief broke down trailered it home had no spark.Ran the battery low when i was trying to get it off the road,got reading in the form someone posted need allot of juice for spark was after cleaning all the wires couldn't figure it out.Charged the battery got spark,that's when i figured gas problem,Checked carburetors had fuel was stumped.Opened gas cap to pull some fuel out to put in plug hole bike fired up,air locked,Was worried something in the petcock was causing the problem.Easy fix going to be a nice weekend here for a ride.Thanks for the replies,help.Not hard to act stupid sometimes.Cheers   

Not stupid.  We have all done things like this.  It is the knowledge on this board that helps us through the problems.
Glad you got it figgered out.

Hay 
Jimmyt

[Michvalk]

Might look in the end of the vent tube for a mud dauber nest