Have one of these?
Is the flame getting smaller and smaller over the years?
If so, eventually it will need to be cleaned – estimated MTB cleanings is about 15 years. Diesel fuel is not quite free of ash – so ash will accumulate in the pot. But more importantly, the diesel cokes out from the heat of the burner, leaving behind deposits of carbon. These accumulate in the bottom of the pot.
But more importantly, the carbon also accumulates in the fuel entrance to the pot, at its center bottom. The feed from the float tank to the pot is strictly by gravity, with the head driving the flow only a couple of inches… it doesn’t take much to significantly decrease the flow when there is only this tiny pressure to drive it.