I have an OS 46 AX engine that will start sometimes and then other times will not . The engine is mounted side ways in a Ultra Stick 40 airplane. Sometimes it will start and fly one time and will not start anymore. I never know when it will start. I need to know what is wrong. Thanks.

We will need a lot more information... what type of fuel, running rpm, running temp...I had a problem similar with my .55ax. never really could find any problem, but after rebuilding the fuel tank, plumbing and cleaning the carb(where I never found a problem with any of it) it started running like it was supposed to. I would suggest back flushing the carb out and ensure that there is nothing on the needle valve or in the needle valve housing(its easy with that needle valve remote, just hook up the fuel pump to the side closest to the carb and pump it a couple of times). Keep us posted with specs if you have any results.
dan

If the engine will run and run well throughout a full tank one time, but not start another time, your difficulty is really not with the engine, iteself. You're either flooding the engine or letting it be dry of fuel. It's down to technique. You should set yourself the exact, same procedure each time you start the engine. Make sure it's not flooding between flights. Many engines are mounted such that fuel in the tank will siphon into the engine. The engine will be too rich, and become very hard to start. One way to prevent siphoning after the engine has been stopped is to open the throttle to full, put a finger over the carburetor air intake, and slowly turn the engine backwards. This will force the fuel in the fuel line back into the fuel tank. When the fuel line is full of air, fuel in the tank cannot siphon into the engine. You do need to make sure that there's a small loop of fuel tubing that is higher than the level of the fuel in the tank for this to work.

The last two days I flew it would not start until I put fuel into carb. It was getting fuel to the carb but was coming out the top of carb. Its like the fuel just was not getting to the crankshaft.