Wasn't sure whether to post here or in the softail section.


When I was disconnecting the fuel tanks on my '96 softail I pulled off the top tube that connects the two tanks (the one under the dash panel) and it hissed for a couple seconds. Should this happen or are the tanks not venting properly?. Any info would be appreciated. Cheers.

 

Sounds like your vent is plugged. the cap on the right (throttle side) is vented. Tank isn't under vacuum.

 

So there shouldn't be a build up of pressure then. Thats what I thought but wasn't sure. I've got an intermittent fuel problem so just working from top to bottom until I get it sorted. Handy to know its just the one cap thats vented. Cheers for that.

 

I think you found your problem...

 

If you flip the cap, you should see the vent hole. Clean it with a pin or paper clip.
If the air cant get in, it creates a vacuum and stops the fuel from flowing.

 

Cheers for the replies. I'll check the cap out and see what happens. I'll let you know if it solves it.

 

Incidentally, you still need a tank vent for pressure. Not your problem here though. The vented cap allows atmospheric pressure to push the fuel to you carb, but it doesn't and shouldn't allow pressure inside your tank to be relieved. The pressure is relieved through another point (if you have a charcoal canister, it goes there. Otherwise a tube/hose, (possibly with a small filter) open to the atmosphere. A couple symptons of a NO or a plugged pressure relief would a "flooded" carb or gas seeping out the filler neck on to your paint.

Also this is "Theory"...apply as needed
.

 

Ah right. Haven't noticed another vent anywhere but to be fair I'm not known for my observational skills. I read on another post that the reserve on the fuel tap bypasses the vacuum. Is that right?. If it is I'll leave it on reserve and see if it cures the fuel problem. If it does at least I'll know if I've got a vacuum problem. Thanks for your advice thus far.

 

How bout this...but again, this isn't your problem.

 

The one just below the fuel cap is the one that was hissing.