What could potentially happen if you refuel a forklift while the engine is running?

Refueling a forklift while the engine is running presents significant safety hazards primarily due to the risk of fire. When refueling, the fuel can come into contact with hot engine components or electrical sparks from the ignition system, increasing the risk of ignition. Fuel itself is flammable, but more critically, fuel vapors that are released during the refueling process can also ignite. This is because fuel vapors are highly volatile and can easily catch fire in the presence of an open flame or spark.

In addition to the fire hazard, the other options do not present a direct correlation with the action of refueling with the engine running, making them less relevant in this scenario. Refueling should always occur when the engine is turned off to mitigate these risks effectively and ensure that safety protocols are followed. By turning off the engine, the potential for ignition from both the fuel and its vapors is minimized.