IMO
Did the organizer fill the tank for participant or they DIY? Any JB petrol ram tactic on that day?
Fuel filled by participants at start of challenge, 5mins time allowance. I already give up after 3+mins of "humping".
End of challenge, filled by pump attendant and verified by few marshal, 10mins time allowance. No "humping", but with 10mins time allowance, they keep filling to the brim and allow air bubble to escape.