Try this before you replace the engine. Not sure where you were blowing. I'm assuming into the line that goes to the pipe? Make sure that line and the one to the carb have no cracks or nicks in them. Is there resistance when you blow, or nothing? If it's sat for a while nitro fuel can really gum things up. If the carb inlet is clogged you won't get fuel up the line. If you remove it from the carb can you get fuel to move?
Also crashes can break or crack things. Sometimes they get missed. Make sure there are no cracks in the fuel tank and the rubber O-ring seals when you close the lid. Are you leaking fuel any where? The plastic nipples on the tanks like to break just enough to cause a problem but not really see. You may have to remove the tank completely, but look closely. It needs to be a sealed system to work properly. A crack in the manifold or pipe would be a different issue.