[Just Bill]

Fisrt guess, bad thermocouple. It senses that there is fire and tells the gas valve all is OK. If it is malfunctioning, it will shut off the gas valve. Look at the burner unit, is it clean, free of rust and debris?? Is the thermocouple in the flame when it lights?? If the thermocouple is not in the flame, that is the same as not sensing fire.

 

[DexterII]

I would also wonder if there is some manner of valve that prevents gas from flowing if the trailer is not setting level, or within a certain degree thereof. Might not be a bad idea to chase that entire circuit.

 

[COLDIRON]

Got enough gas? regulator work OK? Other gas appliance work OK in the trailer IE; Stove? Spiders in the pilot line or main burner?