Furnace Pilot Light Burns Out overnight

Bump

Usually Bad gas valve, but tighten the Thermocoupler mount on the gas valve first. Should be 5/16 wrench nut. Hopefully you do not have a Coleman furnace. If so, there are no parts and have been no parts for almost 30 years. Doug

Built in energy conserving device?

Seriously, how big is the pilot flame? Is the thermocouple positioned with the tip centered in the flame? Just guessing, it's colder at night, if right on the edge of keeping it lit in the evening maybe you go over the edge when temps drop. Or maybe the thermocouple is going.

Needs basic maintenance/cleaning. When was the last time it was done?

BTW, I have no intention of looking through your past posts to see what RV you have. Create a signature line or type it into your posts.

1979 Prowler 23'
Coleman Presidential II furnace
Bought the trailer last spring. No idea the last time it was cleaned.

Don't over tighten the thermocouple as you can damage it and or valve. Just replace the thermocouple if you don't know how to check it there cheap enough. Most likely the problem if it wont hold the pilot.

Your furnace probably has an igniter and not a pilot light.

No, it most definitely has a pilot light.

I haven't had the time to dive in and clean/replace stuff yet. I'll try cleaning the pilot and replace the thermocouple while I'm in there.

Is the furnace pilot supposed to be a nice blue flame like the fridge, or is it supposed to be orange? Mine is about 3/4" of orangeish flame.

blue