At 1924 Pacific time, an amateur-built Glasair JM-1 suffered a partial loss of power during initial climb from Hollister Municipal Airport and crashed while maneuvering for a forced landing. The pilot and pilot-rated passenger were seriously injured. The owner reported the airplane had just departed runway 31 when the engine started to run rough. In an attempt to return to the airport, the airplane clipped a tree and landed in a field where it struck a piece of concrete and came to rest inverted. The electric fuel pump, which was required for flight, was not turned on.