If your safeties are holding steady all the way thru to the HSI being energized (the pressure switch is the only one likely to drop out and cause issues at the beginning of a cycle, the rest would not permit any action at all), you have 24 volts across the gas valve for a couple seconds until trial for ignition fails, you hear no click of the valve, or even if it clicks (or chatters) and you smell no gas...
90% of the time it's a bad valve. Just make sure you have gas service. Ignore goofy low voltage readings, they serve no purpose unless you are in controls.
Not exactly a RSES SAM...but it's been my experience.
Great info... I made up a test 24v. Transformer.ext. cord to 115v / two jumper wires. Eliminates quessing board wiring! I have seen 24v to valve,but if its not grounded thru another switch it "wont" open! Note; clicking of valve is not always accurate either..Goodmans latest bulletin states both Hi And Low side power is needed to open gas valve in two stage models.an auditable noise is no longer a true test!
I have had two calls this year same thing.H.S.I would glow but NOT lite the Nat. Gas. I now always test with an open flame "Torch". Repositioning HSI...,or replacement have been my remedy.But to be honest...,not sure why! No call backs yet!
I also sometimes do this to bleed the air from the line if I had to open it for a repairs. Just last night I started up a 12 ton Carrier RTU. I had no air in the line up to the shut off valve. So the only trapped air was from that point to the burner. It took about 10 times of letting it work the air out before it lite. I was just getting ready to get my torch when it finally hit. Had I had my torch handy it would have been one time.