RV-12, 18 hrs, OAT 85. Flew the pattern three times, with a full stop, taxi back and takeoff. On fourth attempt, just prior to liftoff, engine became extremely rough. Aborted takeoff, taxied back to ramp. Did ignition check at 4000 - OK. Made three full power ground runs all resulting in a smooth running engine. Taxied back and started takeoff roll. Again just prior to liftoff engine became extremely rough. Returned to hangar, removed upper cowl and checked engine. No fuel smell, no apparent issues. Fuel pump and hoses very hot. Possible vapor lock? Apparently only occurs above static rpm range. This is first time to have just flown pattern.
Any help appreciated.
Thanks in advance
Any help appreciated.
Thanks in advance