| Author | Message | ||
     Eboos |
Has anyone else had their bike running just fine for miles then suddenly feel like it has run out of gas and die, then start back up just fine after? My bike does this all of the time and I have checked out many different possibilities. Jay at Sheldon's HD/Buell (founder of ATC) told me that it is most likely my fuel tank vent or vent valve that is causing the problem. With the valve blocked up, it is creating vacuum which is not allowing fuel to flow. This make sense, but before I proceed with removing the vent valve (which looks like a pain in the butt), I wanted to check about something. First, according to the service manual, the fuel tank is vented out to the atmosphere through the vent valve, not atmosphere being drawn in. If this is true, how would a blocked valve effect fuel flow? I am picturing it like a water jug. With one hole in the jug, water will flow out drops at a time. With a second hole in the top, water will flow out in a stream. This is because air is allowed into the jug and breaks the vacuum, is that correct? If so, then how can a vent that is venting out effect the fuel flow if it is not allowing air in? Or is it allowing air in? Is the vent or vent valve effecting gas flow in other ways? Would the vacuum pressure from the air flowing through the carburetor be enough to draw enough gas, basicly, from the gas tank without a vent? Am I over thinking this and should I just change the vent and see what happens? | ||
| Jerzydevil |
As the gas heats up, the vent lets air out. but it also sucks air in to allow the fuel out of the tank. without the vent, in a plastic tank it creates a vaccuum and pulls the tank in to allow some air, in the xbs' case, there is no give to the tank, so it dies, when it does, there is no suction at the petcock, so air comes back through and releives the vaccuum, and allows the fuel to flow properly. | ||
| Sportyeric |
It is allowing air in, to fill the volume of the fuel that is being consumed. On my Sportster, which has a vent mechanism in the cap, I went through a similar problem when I put on an aftermarket cap. My Buell seemed to be doing something similar but it turned out to be water in the fuel.A faulty petcock could also cause that behaviour, at least on a carburated bike, if it allows enough gas through to fill the float bowl. After the bowl is emptied, it takes a while to re-fill. Had a dirtbike that did that once. | ||
| Blake |
Yep, the tank vent works both ways, for both exhale and inhale. It has a float though to prevent fuel from escaping during a tip-over, that is the "valve" part. Easy test is to blow and suck on the other end of the vent tube. Just use one mouthfull of air, not your lungs to blow or suck. You generate more force that way. Next time you notice the problem on your Cyclone, if you can do so safely, pop the release tab on the fuel tank cap. If the bike regains good power, you've identified the problem. I wish folks would post this kind of stuff to the Knowledge Vault. | ||
| Eboos |
Sorry Blake, feel free to move it. There just doen't seem to be enough traffic in the Knowledge Vault. Also, with so many options, the KV is great for looking up things once questions have been answered, but the same options work against getting those questions answered. |
