A torch ignitor for a lean burn internal combustion engine is disclosed in which a small quantity of gaseous fuel is activated by exposure to an electrical arc and injected into the main fuel air charge in the combustion chamber. The arc is established by causing a current to flow to a pair of electrodes which are separated by the application of the torch fuel under pressure to generate the arc. The arc is caused to migrate about the space between the electrodes by the impingement of the fuel flowing through the space.