E30 Zone

Hello - I recently got the local garage to replace a fuel line under the bonnet ( I was away otherwise I’d have done it!) and it’s has failed to start ever since. They claim there’s some sort of security isolator ( there isn’t ) but I’m a bit stumped - engine spins but no fire.
On closer inspection today I have a feeling they may have dislodged a plug/ sensor. I found this 2 pin plug disconnected - but I can’t see what it is or where it goes? Speed sensor? The car is a 1989 325i and it’s never not started before…
Any ideas on what this plug might be? Can’t see it on the wiring diagram

Hard to tell from the picture but it's more than like to do with emissions. If your car is fitted with a cat' then this would plug in under the throttle body and go to a charcoal canister bolted to the inner strut tower. If the car has no cat' then it just dangles free. Probably nothing to do with your non starting issue.

Ah ok thanks - there goes that theory.. I don’t have a cat but maybe they’d started including the wiring by 1989

Turned out to be the fuel pump!