engine cranks over but wont start pump does not swicth on on 2001 Mercedes-Benz S55 AMG

was not crankin after leavin it over night starts cranking but wont start

Asked by for the 2001 Mercedes-Benz S55 AMG
maybe you have a fuel or ignition issue.
how do i check for the problem
1 more answer
When I had this problem it was a crankshaft position sensor. Mechanic said it was very common issue.