Car Wont Start

I have a 1988 535i BMW that I bough 2 days a go from a guy who parked it 6 months ago. It has a a 3.5 L V6 I do believe. My question is the car will turn over but will not start. I can smell gas while trying to start the car. I also notice if I press the gas pedal to the floor, there is a switch or button not sure what you would call it but it sticks out of the floor by like 2 inches, and if I press the gas pedal all the way down and the switch it pressed and then with the pedal still all the way down and the switch being pressed I try to start the engine it makes a pop noise and this cloud of smoke comes out of where the air box hooks up the engine and it smells strong off gas. Im guessing if I smell gas my fuel pumps arnt bad. Sometimes when trying to get it to start it ends with a tump noise. Any ideas of what the problem could be?