The pilot reported that while conducting pre-flight checks, the fuel drain sample contained water, which he described as a common occurrence for this aircraft. He drained the fuel until he obtained a clear sample. He took further samples, including after refuelling, until satisfied that the fuel tanks were free from water contamination.
The aircraft took off from Runway 23 at Coventry Airport, with the pilot reporting the pre-takeoff engine power checks and after takeoff checks being normal. After climbing to 2,000 ft, the engine began to run rough. The pilot turned on the fuel pump and informed ATC he would be returning to Coventry, but the rpm continued to reduce and the engine subsequently stopped. He selected a different fuel tank and restarted the engine, but the aircraft could not maintain height. He chose a field in which to land, electing to keep the undercarriage retracted due to the ground conditions and to maximise the glide range. The forced landing was successful and both occupants exited the aircraft without assistance.
The pilot considered that the engine failure may have been caused by water contamination in the fuel, carbon build-up on the spark plugs, or some other problem.