It fires up but won't stay running. - Reddy Heater-170,000 BTU Kerosene Deluxe

Mine were doing the exact same thing and you would not guess the problem! Water had built up in my tank from condensation, it was pissing me off. I did how ever manage to pull my preventative maintenance on it. I would suggest the same for you. Remove the top half of the heater cover, locate the burner tray, on the tray there is a flame sensor. Remove it and clean with windex and a soft terry cloth rag, replace it and be sure it has an unobstructed view of the flame. Next is the fuel system, locate the nozzle, remove it, now they say that you can not clean these but I say with a q-tip, tooth pick and carb cleaner you can. Directly behind the nozzle is a screen these corrode while in storage, so clean it as well. Put this back together, and now inspect all of you fuel lines for hole, cracks,and dry rot. Put the top half back on the heater and now remove the side cover where the fuel line goes thru to the fuel tank, once you do this you will find an in line filter remove it and clean with a compressor and air gun, blow air backwards thru the filter, now it is clean. Put it back and again inspect the fuel lines. Last is the air filter at the back of the pump, it will be foam rubber, remove it, and wash it out, make sure to dry this real good, and now put it back in. You have now completed your yearly maintenance. Happy heating. Please check your fuel tank and clean if necessary, I over looked this on mine!