The landing runway was obstructed by a vehicle when the pilot returned from a local flight. He was not surprised, as there is unrestricted access for vehicles at this unlicensed airfield, so he flew two missed approaches. However, the vehicle driver seemed oblivious to the aircraft and remained on the runway.
With no accurate fuel quantity indicator, the pilot became concerned he might run out of fuel. Therefore, on his third approach he flew lower, hoping the driver would notice. The vehicle moved clear just as the pilot was about to reach his nominated go-around altitude, so he continued the approach while trying to watch the vehicle. Then, as he flared for the landing, the pilot noticed the airspeed was lower than normal. He thought it safer to continue than to attempt a go-around; however, the rate of descent increased and the aircraft landed heavily.
Some structural damage was found after the flight and, upon draining the fuel, the pilot discovered his endurance had been greater than he thought. He judged his heavy landing was due to distraction but observed that the perceived fuel shortage had created extra pressure, so he has decided to improve the fuel quantity indication system.