car wont start at times

[ulkesh]

i have an old BMW 1 series which has no other issue but that at times it refuses to start no matter if i try for an hour and at other times it gives me no problems.

as this is not constant how can i diagnose the problem.

any clues to where i can start the search from.

[Sumer65]

In such situation first doubt goes for changing the crank position sensor. 90% it shud solve it.