02 dodge caravan want start

I have a 02 dodge grand caravan and when I
attempt to start it. It want start.it will crank like it
wants to start but it want start.it also seems as if I
smell gas when It is cranking. I also noticed that I
have a oil leak under neath the van.I have changed
the spark plugs and wires,put in a new battery and
starter and the fuel pump seems to be still working
because when I turn the key I can hear the fuel
pump starting from the gas tank.don't know what
the problem can be.