The latest bulletin has arrived from the DVSA (VoSA)which refers to fuel leaks.
There has been a change in policy with regard to the seriousness in which these are held. It has now been decided that with effect from 1st September vehicles with defective fuel systems will be issued with an immediate prohibition. This means fix it on the spot or have it towed away.

This is one of the more difficult problems to overcome on older fuel injection equipment. It does not like modern ULSD to begin with with the consequence that leaks from the injector pump are more common than in the past. Many of these older pumps are designed to let fuel that leaks past worn elements to dribble onto the road. The closed circuit systems which return it to the sump are not particularly efficient with the result that the fuel leaks out where it can.

This is going to be good business for the fuel injection specialists.

https://movingon.blog.gov.uk/crackdown-on-defective-fuel-systems/