Cut out and won’t start

[KitsonRis]

When I go to start the car it starts than then just runs out of puff within 30secs and cuts out. Then it won’t start. Cranks all fine, immobiliser light off, fuel pump primes. I got the AA out the other day for it as I was a bit stuck, took about 20mins to turn up and it fired up first time. He then continued to rev it lots (not impressed as it was cold and he hit the limiter a few times) and was fine. Checked the battery charging voltage and it was 14V but the battery is a bad one and I need to get it changed. It’s done it twice today and the latest is it cut out while driving (where I currently am now as I managed to swing it into a side road while I wait for a bit before trying to start it again).
Any suggestions? It’s a Ph1 172. My thoughts are crank sensor. But anything else to check? Googling comes up with various stuff and the one I am not liking is bad earth/loom.

 

[JamesBryan]

Could it be your inertia switch.

Ph1 has a fuel cut off switch in the engine bay, possibly dodgey?

 

[KitsonRis]

tried that, doesn’t look like it has activated but have pressed it to see if it does anything. Thought that cut the fuel pump but I can hear that prime.

 

[KitsonRis]

As per usual when the AA turned up it fired up first time. Piece of scrap that it is. He thought crank sensor too so that is going to be my first point of call to change