my oil furnance is not lighting every time the themostat calls for heat. Sometime it works fine and other time it will not light and i have to press the reset button and then it sometimes does not start. Fuel is getting into the fuel chamber. Sometimes the furnance will light after alot of fuel has been pump into the chamber with a loud bang. Please help

You have a ignition problem.
Weak ignition transformer or
Defective/dirty spark electrodes or
partially restricted nozzle or
Loose wiring.

I do not recommend operating this furnace under these circumstances.

If the reset is pressed to many times and to much oil gets into the combustion chamber not only will you have a loud bang but you could end up with a uncontrolled burn which can lead to blower fan/fan limit control damage to say the least.

if you are not familiar with a oil burner and can do the necessary repairs I suggest you call a professional repair person and get it fixed ASAP.