Ommony - found this tidbit while looking for pump configuration:
" Some Rovers have an water and dirt separator mounted on the chassis rail on the rear in one of the dirtiest positions on the car. It augments your main fuel filter's life considerably. It must be purged once a month. Wear plastic gloves for this. Simply unscrew the wing nut at the base and let the mixture flow out into a small jar. If water is present you must repeat the purging daily until no more water is present. Then you can return to a monthly purge."

Maybe worth investigating.

86 Isuzu Trooper TD 5 speed
82 Isuzu Diesel I-Mark
86 300 SDL MB 126
85 300SD MB 126
82 300 D MB 123