Just found out the heater (suburban NT-16s) is leaking gas. This is causing a gas buildup and a significant "whoomp" once it re-starts. If it has been off for a while you can smell gas buildup in the camper. I finally traced it to the furnace - and gas was free-flowing from the furnace when it wasn't running.

Could it be anything other than the gas valve in the furnace? I am planning on disassembling, cleaning, installing a new blower and gas valve and hoping that solves the problem.

Could just be a connection that is loose. Try the bubble test on all the connections first. If it isn't that I have no experience, so no advice.

I had the same problem, on restart, the spark would engauge and be a delay ignition while the gas valve was open. This would cause a build up of gas in the combustion chamber. It would ignite causing a pop or almost a backfire explosition. I had only to replace the spark ignitor. When the spark ignitor gets old or there's a carbon build-up on it, the spark isn't strong enough to ignite the gas.

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Les & Patricia
2006 22ft towlite (replaces 97 21TL)
2006 Toyota tacoma pre-runner 4.0 L V-6 quad cab
w/ 98 chevy Powervision towing mirrors
2017 Chevy Silverado 1500 5.3 v8 (replaces Toyota)
2 Hobie mirage pedal drive kayaks