So RF cant be convertet to MJ. If you look at the GUI of the engines it shows that it produces RF.

BuildCraft version: 7.99.15
Forge version: 14.23.2.2611
Link to crash report or log: Doesnt crash but malfunctioning
Singleplayer or multiplayer: Singleplayer
Steps to reproduce: Place a Wooden Kinesis Pipe and a Forestry engine (i.e. a Biogas Engine) next to each other with the engine facing to the pipe. Fuel and fire the engine. The engine will start but wont connect to the pipe.
Additional information: No

Thanks for the report! This is actually a duplicate of #3760