Can't fill up with petrol.

How do I fix it

Cheers

Could you be more specific ?

I can only get about 25 petrol in.

Seems the tanks not venting?

Thats a strange one considering fuel tank vents when you open filler cap. Thats why you most of the time hear psssssss.

Poss vent valve??

are you ramming the nozzle in all the way? My old classic struggles sometimes i fill up and twist it 45 degrees and it seems to work

Have you had a go at googling it? as it brings up a load of stuff on why it won't fill have a look at the charcoal canister under the rear bumper, the lines get clogged and either need unblocking or the canister needs replacing.