my mates z stinks of fuel when started and even more so when he boots it any tips? its definatly not fuel pipes as they have been replaced 2 times?

i had this problem, cleaned the terminals on the yellow ecu temp sender, all was fine after. What fuel is he using or does he just put any fuel in as this can sometimes cause it as ecu has to keep re learning different fuel types. I usuelly try to run on V power or tesco 99 ron, but in emergencies i have had to put 95 ron in the car and can feel the difference car runs shit and get smell of fuel

99 ron carl