This sounds like a control box fault and may need replacing however without more detail its hard to say. check the fuel pressure if you can, make sure you are getting a constant pressure and not drawing in air from the oil filter. once lit the control box is looking for a flame, if flame is lost it may try a few times to light but should go to lockout after a few cycles . check the fuel pump solenoid and valve if they are faulty it may explain why there is a problem i belive it is a 240v solenoid. The metal surround with a round nut ontop of the fuel pump needs to have good contact on the top of the pump to work correct.
farmer, March 2010
