06 Sporty vacuum petcock

[jchcobra]

Last few days my 06 1200 custom quits going down the road. Pops a few times and then just quits as if out of gas. I let it set for a minute and starts back up and goes about a mile or so and quits again. Removed carb bowl and not enough grime to cause float to stick. Tank filter looked fine, only slight amount of crap from gas stations. Have ruled out dirt and float problems but am questioning my vacuum operated tank petcock. Bike used to backfire violently before making the cure with jets etc. Is it possible that all the backfiring has taken it's toll on my vacuum diaphragm in petcock? Vacuum line is on carb and all else looks normal. Any ideas anybody? Until this problem started a few days ago, bike has run real strong. Stage 1 with Vance and Hines 2 into 2 pipes. Now afraid to go anywhere till I find the fix. Thanks for any help / ideas.
jchcobra

[andyxlh]

I tested the one on my FLHR by removing the fuel line from the carb, and the vacuum line. turned the fuel on and sucked on the vacuum line. The fuel should come out of the fuel line (not into the vacuum) with suction on the vacuum line. If not, then the vacuum switch is bad. Replaced it after having a failure like you describe with one with no vacuum switch, I have no problem with turning the fuel off myself. If you do thet you need to plug the vacuum line with something.

[FSG]

It may well be the vacuum switch in the petcock as Andy suggests but it may also be the vapour valve in the tank vent tube line.   The first/easiest check I'd do is loosen the tank filler cap so that air can enter and then go for a ride, if it still quits then proceed with Andys suggested check of the petcock, if it runs OK then you have a blockage in the tank vent line / vapour valve that is stopping fresh air from entering the fuel tank allowing flow of fuel.

[jchcobra]

Thanks guys,
I ordered a new vacuum petcock from my dealer and as soon as it arrives, I'll know more. I checked out the vapor line and you can not blow through it but can draw air in the upward direction (toward the tank). When I pulled the hose off the underside of tank, you could hear a release of pressure as it had set in the sun for a while. I am assuming this is right?! Right now I am waiting for my new petcock before venturing out on a two or three hundred mile ride. Thanks again guys, we all need a little help from time to time.
jchcobra