So today i had my ecu looked at and all is fine.
the guy who looked at it suggested it could be my crankshaft sensor, problem is i have no idea where this is

could someone please point me in the direction where this is please

What is happening is when trying to start it wont fire and will backfire it will turn over getting fuel etc but doesnt fire, leading up to this i was driving through a water never stationary and nothing to deep (also have snorkel) then parked up for awhile and started of again and it stalled about 100m from where i parked up and wouldnt start again, after a long tow home pulled apart and noticed crank had moved about 90 degreees prior to all this happening i had replaced water pump and cambelt and a few tensioners etc, please help i am all out of ideas.

Truck is a 1993 3.5 v6 swb pajero
Thanks
Chris