I am using it with O2 and propane using Gentech preset regulators.
I turn the fuel on 1/8-1/4 turn, then try to light it.
I'm not familiar with Gentech regulators but the explanation you use
would make it seem as if they are for disposable tanks. If this is
the case, and they operate like the Smith regulators, then they must
be completely opened. It also sounds as if you may have to much fuel
when trying to ignite the tip, as a matter of fact I find for first
time users this is the most common mistake. The Little Torch handle
adjustment knobs are very sensitive and require a fine touch. Also,
make sure the O2 is off till you get the fuel adjusted to the
desired size, then slowly add oxygen.
Hope this helps,
Rio Grande Technical Sales and Support
800-545-6566 ex 13903