To begin with, correct the word “petrol” in the question. If the engine is just an internal burning machine as in cars then only a high quality petrol is used as fuel. The planes equipped with jet engines use only aerial kerosene. Though this kerosene is of high quality, is not petrol. After being squirted into the jet engine the kerosene burns explosively. The hot air produced of it forcefully threshes backward, and hence as per Newton’s law the plane gets a push. Boeing-747 jumbo jet uses up approximately nine liters of fuel in less than two seconds. But at the time of take-off it is filled up with 1,77,000 liters of fuel, and so the supply lasts for hours. (In 1946 one of the South African jumbo jet had had a non-stop flight of 16,465kms from America-to-Africa, yet at the time of landing it had in it the fuel for two-hour-long flight)
One more interesting thing: There is no separate fuel tank in an airplane, as there is in a car. The fuel is generally filled in the hollow made in four parts in the wings. Each part thus is a separate fuel tank. Any part can pump in to any engine in the plane. As the tank on one end empties, apparently it leads to a change in the gravity centre point and causes imbalance. Hence in order to maintain balance the pilot keeps on shifting fuel to the emptying tanks from the other tanks. For more information observe the diagram above. The fuel carrying capacity of Boeing-707 is shown.