Car wont start!

[hacer1027]

2005 E55. While on my way to dinner car drove fine, 2 hours later I go to start car and cranks over, but wont start or starts for a second or two very rough and then stalls out. I have half tank of gas. My factory warrenty just expired in May, before I tow to stealership any last minute suggestions? (fuel pump, fuses, fuel pump relay?) thx

[Musikmann]

Try replacing your Crankshaft Position Sensor. That is a common cause that might explain your symptoms.

[hacer1027]

Thanks, I will try that first thing tomorrow and follow up with progress. Where is the Crankshaft Position Sensor located?

[hacer1027]

Crankshaft Position Sensor was not the problem stealership told me the relay burnt out fuel pump sender unit, and harness. $ 1695.00 to fix. thanks again.