1.5 carb engine won't start, carb problem?

Just brought a non running 82 mk1 cabby. It's got a 1.5 engine and a basic weber carb on. Car turns slowly and fuel runs into filter and for some reason part of the petrol pipe is clear and I can see petrol going towards/into carb. So petrol pump isn't at fault. 
Previous owner said putting petrol direct into carb works although I haven't tried yet
I'm hoping people can give some possible problems so At the weekend I can try and pin point the problem. 
Thanks in advance

Got this running rough today. Was backfiring up the carb abit and misfiring so I need to sort timing out. It's got a weber 36 carb on and vacuum pipes seem to be all over the place and some missing and others going nowhere. Anyone got any diagrams for vacuum set up? Was one in the how to section but pictures are deleted. 
Thanks