I'm going to start chasing this problem in our pup and thought I'd seek input for avenues that I haven't considered from the collective knowledge here. Unit: Atwood 7900-series furnace (exact model not yet identified), in a '95 Coleman Utah. Problem: Inconsistent lighting of burner. Happens when running from battery or shore power. Symptoms: Sometimes the furnace lights right up on the first or second click of the ignitor cycle; other times it may take six or eight sparks for the burner to light. Sometimes it doesn't light at all through several ignition cycles. And the worst case is it will light the burner after loading the combustion chamber with propane and make a hellacious BANG! No other LP appliances are running when this happens, though I haven't checked if there's any difference if the galley stove is lit. The external stove is on a separate high-pressure line. I have taken to lighting the galley stove after setup and running it for a few minutes to purge the gas line. Plan of Action: I'm going to do as much inspection of the wiring (I have the manual and diagram) to make sure that PO's haven't mis-wired anything over the years, as well as inspect and clean the burner (if I can remove it without removing the entire furnace) and the ignitor. Will also check the gas lines (regulator to furnace), valves and solenoids to make sure they're clean and operating properly. I've also learned the correct anticipator setting for the thermostat and will dial that into the correct range to the Atwood specs (0.48 amps). Previous History: The PO had replaced the thermostat with an analog White-Rogers unit thinking it was the cause of non-operation, and the furnace wasn't working when we purchased the pup. I found that the time-delay relay was bad and replaced it and the furnace started working but with the problem as noted. I also had to replace the LP regulator due to a leak in the (very old) service selector switch - it's a two-tank setup. Any input would be welcome! Thanks!