Do u have a a fuel filter? clean the GAUSE out and blow through it.
Also, obviously you buy fuel from hobby shops?
Check you have no blockages in your carb with water or yellow honey looking gell throughout your engine. Most hobby shop fuel , after a while in your engine you will see yellow honey gell form in your engine. This is causes because of poor fuel. Hobby Shop fuel is "usually" made in china.
Try and get your hand on Angus Nitro, made in U.S.A but availible everywhere. It is best for your engine and has best quality.
Also,it sounds like a good case of "Glow Plug" , unscrew the glow plug out the top of your engine and put the glow starter on it and see if it glows. If it glows its ok, if it glows but takes time, i suggest u replace it.
This is all i can think of, but you should pull your engine down and check it. Just make sure that when u put ur engine back together, clean it out with nitro,unleaded fuel to clean all dirt or dust.
" It takes a lot of things to go right, but only one thing to go wrong to lose a race "
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