My first thought would be the thermal fuse link. If you are getting gas (you can hear it or smell it) then this would be my first guess. You can bypass it, that is the quickest test, by taking it out and pluging directy into the circuit board. If it ignites, then the thermal fuse link is bad. As soon as you can, replace the thermal link as it does serve a purpose -- prevents fires caused by backflow flame. You can search this forum and find lots of discussion re the thermal link.
Dave and Karen -- '02 Ultimate Advantage 36 C, 350 HP Cummins, Allison 3060 Tranny
'07 Ford Escort, Brake Master 4160, '13 Ford Edge, InvisiBrake