We have an '89 jayco with a 5 gal. Hot water heater. The pilot light won't stay on after lighting, holding the button a couple minutes. It will just go out. I replaced the pilot light burner and thermocouple a year ago when the problem started and haven't had any luck with it. Didn't camp much last year so didnt worry about it (thanks covid). But now we have a couple trips planned and would like it to work. The electric part of the heater works but I prefer gas as it recovers faster.

 

Is it electric ignition? (just for info value...)

 

Like my water heater is electric ignition and the ignition probe is used for whats called Flame Rectification. The ignition module can sense if there is flame contact with the ignition probe and it will continue burning. In my case I've got to clean that tip of the igniter of rust and it will continue to burn. 

 

Is if old school match light?

 

The themocouple has to have to have good contact with the main valve assembly to release the fuel valve. It could be a main valve issue since you replaced the thermocouple. But double check the connection to the main valve. If no love you might need a main valve. 

 

It would help to know what manufacture of water heater too. Atwood, etc.

 

Example...

https://www.amazon.com/Atwood-91602-Control-Valve-Thermostat/dp/B002UC18HU/

 

 I want to say it's a suburban? I'll have to look again. 

 It's the old style, no electronic ignition. 

https://www.amazon.com/Suburban-Gas-Control-161111-Manufacturing/dp/B00BFUBJEK/

 

 Yep, that's the one I have.

 Expensive little bugger.

Before I buy a new one I want to test the thermocouple.