Hey everyone, extremely new to this forum but it seemed informative. My wispr recently stopped feeding butane through the system, I have tried to "purge" the system by letting all the butane out and letting it sit, multiple times. Still no avail. =( It will not put any gas into the system so there is no hissing or no ignition.
OK, here's my 'take' on the Iolite (I don't have a Wispr but the idea is the same). Liquid or gas phase fuel (either one, depending) is available to the demand valve when the control valve allows it (you turn it on). The demand valve has a very tiny aperture in it such that all it can pass is vapor (any liquid that makes it that far has to boil on the spot as the pressure drops as it goes through the aperture. It can't be liquid at 'room pressure and temperature'. Normally the demand valve snaps open and closed using a deadband of perhaps ten degrees (?), the point being it's open full or closed. The actual gas flow may lag the valve a bit as the pressure bleeds down but it generally is on or off. Temperature is controlled by duty cycle.
So much for the ideal. In the real world, the fuel is not pure. Not only is it a mixture of similar hydrocarbons (AKA old dead dinosaurs) but it's a great solvent (which is why guys make hash with it). There's all sorts of dead dinosaur and other stuff potentially in there, the stuff that leaves the deposits on the mirror when you do the mirror test amongst others. Normally it all burns. Normally it gets washed through the system by the huge volume (relatively) of solvent. Just like the lime and other minerals in your tap water.....
Only, like the lime and minerals, conditions can cause the dissolved stuff to condense out. Unfortunately I figure it's in our valve, specifically the aperture itself that the mischief happens. Once the deposits form, it's near impossible to remove them. What I found worked in my case (I foolishly used cheap fuel.....) was dumping the bad gas in the normal fashion and filling it up with the good stuff. I then left it 'on' on the patio overnight. It didn't light of course, and I couldn't hear gas flowing but it was empty the next day. This was in summer and I left it in the afternoon sun since Butane pressure goes up quickly as it gets warmer, I doubt it would have worked at low temperature. A while later I had occasion to use my backup unit (since given away) which had been stored filled for a while. It sputtered and didn't seem happy so I shut it down, let it cool, then opened the valve again and let it run down I bleieve washing the varnish or whatever it was away in the process.
I could easily be all wet, of course, but it's easy and cheap to try. And like chicken soup, 'can't hurt, might help'. Good luck.
OF