On October 31, 1998, about 1330 central standard time, an Ercoupe 415-C, N99924, registered to an individual, collided with a power line and crashed in a field while making a forced landing following loss of engine power at Hartselle, Alabama, while on a Title 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft received substantial damage and the private-rated pilot received serious injuries. The flight originated from Roundtree Field, Hartselle, Alabama, about 1245. The pilot stated this was the first flight since extensive repairs and restoration to the aircraft. After takeoff he departed the airport traffic pattern and climbed to 3,500 feet. He performed maneuvers for about 30 minutes and then returned to the airport traffic for takeoffs and landings. After the second landing, he again took off. As he turned onto the downwind leg, the engine quit without warning. A quick attempt to restart the engine was unsuccessful. He selected a landing site for a forced landing and turned toward it. He was unable to maintain sufficient altitude to clear a power line and the aircraft collided with it, causing the aircraft to nose down. The aircraft then impacted a ditch and bounced and landed on the landing gear, from which a normal landing roll was made. Postcrash examination of the engine was performed by FAA inspectors. The spark plugs were found to have black soot deposits. The exhaust system also had black soot deposits. The engine was started and operated at idle power for a short time before quitting. A higher engine power was not attempted due to a fuel leak from fuel line damage during ground impact. The Bendix-Stromberg float carburetor was removed from the engine by FAA inspectors and taken to an overhaul facility. The float was found stuck in the full needle valve open position. Excessive solder on the float fulcrum was contacting the edge of the bowl causing it to stick. The carburetor had been modified in accordance with Bendix-Stromberg Service Bulletin 84 which calls for installation of a new style needle valve which in turn calls for adding of solder weight to the float fulcrum. The service bulletin warns that the added weight should not interfere with the movement of the float. (See attached FAA inspector report)