+1 ^
If, on tick over, it p!sses diesel out of that nozzle, it means that it is not blocked off internally. To block it off you just need a bit of hose of the same ID and some means of blocking it, i.e. something inserted in it and possibly a tiny jubilee clip or even just a good cable tie. One came off on mine on a Mway, not the end one, and diesel ended up over the back window and sadly inside the brake drum. So I wouldn't chance it!