Hello friends! I'm desperate for help. About a month ago, while riding in the woods, my 2011 YZ450F started to fail until the engine stopped. I restarted the engine, it ran for about a minute and died again. After this it didn't started anymore. My Power Tuner indicated error 33 (ignition coil not receiving signal). Ok, I took the bike back to my mechanic, we tested all the electrical system (following all the steps shown in the Owner`s Manual) and everything was OK, including the ECU. In fact we also tested my ECU in another YZ450F and it ran ok. Also, the fault code disappeared from the Power Tuner. After assembling again the bike started and ran properly. I took the bike to a Yamaha dealer, who tested everything and had the same diagnostic: the bike has nothing. After that, I rode for about 2 hours without any problem. One week later, after only refueling and washing (I have the bike for one year and it was always refueled with the same gas, same station, and washed just like the same) and the symptoms appeared again. It ran for about 2 minutes, without idling, stalled and did't fire again. No error in Power Tuner this time. Please, I really need to help, because nobody can find the problem with my bike. I was seriously thinking in selling it after this, but I want to give it a last try. Thank you very much for your attention!