Bonneville America Forums Forums Technical Forums General Tech Still Stallin'

Well now that I have rejetted and can't stay off full throttle, it is easy to get her to stall. But the problem is narrowing down. It only happens once the tank has depleted about 2 gallons, while running her hard, and I can trick it out of stalling by cracking open the gas cap and resealing. So it is definitely some kind of vacuum build up.

Gotta be that vent tube, or at least maybe the entrance to it!

Has to be the vent tube or something blocking the vent port.

If a little gas has gone down the vent hose, it would slam the rollover vent at the end of the hose shut. Also, the hose is really easy to pinch closed.
An off chance, you can see the tube the hose attaches to on the right side of the filler neck, make sure that a bit of paint hasn't come loose from the neck and blocked the vent tube.

Next time he's over this way we'll pull the whole vent system out and give her a good old fashioned air blow job. I'll check it for paint chips too, that's a good call there.

And for all that are dying to say "I told ya so", feel free, I got thick skin. But I tell ya, those metal clips and the AI stuff were not like any other and really close to the plug wires/cap.

I have not stalled out since the other day when I cracked open the gas cap at the first sight that she was shutting down. I was wondering if breaking the vacuum that way dislodged some little blockage like mentioned here. I am praying it's over, but will not turn down an air blow job -be it old fashioned or sloppy.

I just noticed this quote from Greybeard on a thread about the reserve gas capacity:

Quote:
There is a potential problem filling the tank to the max. On non-CA emissions bikes, if as much as 1/2 oz of gas manages to go down the vent hose, it will close the rollover valve at the far end and your bike starts starving in maybe 80 miles or so.
Sometimes you need the extra range, but thatt's something to be careful about.
Unquote

Hmmmmmmmmmmmmm.....I wonder........

You should be able to remove the vent tube from the tank by reaching up under the tank on the right side. I figure you probabyl already know this!

Blow into the vent tube from the tank side and you should not get any back pressure. If you do, it's blocked.

If it's blocked, it will create a vacuum. As our systems are gravity feed, a vacuum in the tank is a bad thing.

With a very low gas tank today the bike was repeatedly trying to stall out and each time I could head it off by cracking the gas cap. Dinqua and I had a date to put in some new needles and while the tank was off he determined the vent in the tank itself is plugged. A pipe cleaner wouldn't go very far in from the top due to the bend in the vent line and nothing was dislodging from underneath which could take more of the pipe cleaner. Dinqua thinks I may have a warranty tank on my hands as the vent line in the tank may not be cleanable without getting inside the tank.

I would definitely take it back as a warranty issue.

Just in case you want to try this, here's a method that may clear the blockage. From a chemical/scientific supply house, obtain a rubber cork (one with a hole in the center) large enough to fit tightly in the filler neck. Drain the tank completely, turn off the petcock, and introduce some compressed air into the hole in the cork. The vent hole is the only escape avenue for the air so anything blocking it should be blown out.

Phil,
Last night when Bob came over I put a piece of hose on the vent tube at each end on his tank. No way could I blow through it in either direction. And as you know, I am quite the blowhard. It is defenitely plugged up. I tried to stick a pipe cleaner in it to see if I coutube seems to take an immediete 90º bend that is too sharp for the pipe cleaner. I then shoved it in from the underside and got about 6" before it just stopped and would not go any further.
I don't see anyway to clear it out or even get to the tube without destroying the tank since it's all inside the tank. Looks like a new warranty tank is called for.

I ran into this problem on my bike a couple of weeks ago. I took an 18 gauge(might have been 20) piece of solid copper wire and fed it down through the vent in the gas tank. Had to go slow and feed it with a pair of duck bill pliers just a half an inch at a time once I got to the bends, but it finally came out the tube at the bottom of the tank. I stuck a paper towel under there while I was feeding the wire thru and all I got were a few paint chip looking particles. Didn't look like enough to clog up the vent line, but I haven't had any gas tank pressure problems since then.

You should be able to find small spools of the copper wire I used at your local auto parts store. Stripping off the insulation seem to ease the trouble to feed it through. Using some wire feeding snot would probably be an even better way to do it, but I was too lazy to make the trip to Home Depot or Lowes.

Of course if my bike was still under warranty, I'd have taken it to the dealer.