Oil furnaces use fuel pumps to pump the oil that runs the furnace. The fuel pump has a strainer which is attached to the blower unit. If this is dirty, the pump will get clogged. So, when you clean or replace the oil filter, it is always a good idea to clean the pump and strainer.
Step 1: Remove Cover
Remove the cover of the pump housing by unbolting it. The cover is located where the oil line enters the burner.
Step 2: Take Pump Apart
There is a thin gasket that will be around the rim. This should be removed next. Next, you will remove the strainer, which is just a wire mesh screen often in the shape of a cup.
Step 3: Clean Strainer
To clean the strainer, soak it in kerosene for a few minutes and then clean it off with the toothbrush.
Step 4: Damaged Strainer
If, after you clean the strainer, you see that it is damaged, bent or torn badly, it should be replaced by a new one.
Step 5: Assemble
Put on a new gasket and replace all other parts as they were.