Disco 2 V8 X reg Intermittant starting issues

hi
the V8 is not starting..it has an LPG conversion .. i know its not going to start as the temp gauge needle sweeps to hot and back again then cranks fine but doesnt start..cant hear pump priming or anything..can hear a couple off relays clicking tho
when its running fine i know its going to start cos the temp gauge needle just moves slightly when turning ignition key and off she goes.
AA couldnt fix it..the report said the injectors were not getting a signal
indie garage couldnt fix it as it wasnt starting and the diagnostic software couldnt communicate with ecu
so went to indie garage to hand in log book for scrapping and it started
took it home and ran it for few weeks absolute no problems and today its not starting again.
the alarms been coded out
ive checked all i can see..even ecu behind glove box...the inertia switch is fine ...the fuse box under drivers column was a bit corroded so fixed that up and still not starting ...also cleaned up engine bay fuse box ..it was ok but cleaned it up anyway
a web trawl threw up a defender td5 having same issue...a contributer described it as the " classic blue connector problem".
so is my V8 suffering from the same ?
any pointers on where to check next

it could be your security system acting up
or... if your battery is cranking over the engine, you have no spark, and you have no signal to the ECU it could also be the crankshaft position sensor (CPS) crapped out on you.
It's on the left side of the engine and kind of hard to get to but be patient. There is a cover you remove then remove bolts to sensor and pull it out to replace it with a Bosch #ERR-735 / #0261210158.

ok juke. thanks for that. ill check it out