To make a long story short, I bought a rental property and the equipment (Rheem) has not been run in 2 years.
Listening to the sequence of events (gets to the gas valve opening and then quits) I figured the HSI was bad. I tested it and got an OL reading, so I purchased a replacement, it tested at roughly 55 ohms, so I installed it. Went through the same sequence of events and would not glow.
The thing that kind of confused me was the wiring, it doesn't look like its wired in series like my equipment at home. It appears to be wired in parallel next to the Inducer motor on the same plastic bracket on the IFC. I tested the wires and they are not grounded or open. I tested the voltage from the IFC, and got 118 for the inducer motor, but only 0.7 for the HSI, even during the sequence of events.
Could this be a bad IFC? I figured I should ask someone who has far more experience than me (I'm only a tech school grad) before buying a new control board.