2001 clk 320 hard start

[kwikrp]

This is the 2nd time I have had this happen, when you go to start the engine just cranks but does not start. I have sat there and cranked and cranked waiting in between. The first time several weeks ago it started after 15 minutes this time it took over a half an hour then it started. After the first time the check engine light was on but then after a few days it went off. Now it started and the check engine light is on. It is seems like it is a fuel problem, but after it starts it runs fine actually great. Any Ideas I know it is vague and could be numerous things.