Which of the following conditions would warrant the rejection of a vehicle based on its fuel system?

The condition that warrants the rejection of a vehicle based on its fuel system is a fuel leakage at any location. Fuel leaks can pose significant safety hazards, including the risk of fire and environmental impact due to fuel spilling on the ground. Even a small leak can lead to dangerous situations, as gasoline is highly flammable and can result in explosions if in contact with a spark or open flame. It is crucial for vehicles to be free from any leaks to ensure the safety of passengers, other road users, and the surrounding environment.

The presence of a securely attached fuel tank, a tightly fitting filler tube cap, or new fuel lines does not necessarily indicate that a vehicle is safe. While these factors are important for the proper function of the fuel system, they do not address the critical issue of fuel leakage. Thus, the detection of a fuel leak is a primary reason for rejection during an inspection.