I have a Fab-All Diesel heater which draws fuel via a pressure pump from my main fuel tank. I warm it up by pouring 1 ounce of diesel fuel into the base of the heater and light it and allow it burn for about 10 minutes. I then open up the fuel line and everything appears to work just fine for about 1/2 hour when suddenly the heater starts to flame out because of what appears to be lack of fuel. The fab-all heater is very similar to other models like the Dickerson brand. Any ideas to what is going on. I have removed and cleaned the burner and checked the fuel lines to ensure they are not clogged.. Thanks, Barrie