I am driving a hatchback with ph12 engine. Then i parked it to buy something. Then when i get back i started the engine again, but it can hardly start. It cranks but doesn't start immediately. It seems there is no gas but in the meter it has half tank. Then i stepped on the gas several times and while starting then it starts. But if i step out the gas pedal engine stops again. It seems it can't pump gas. Then when it starts i have to maintain stepping gas pedal until the car moves, then when i break and remove my foot on gas pedal it then turns off again. What do you think is the problem with my car?