I have a question on tecumseh engines and these are not old but I'm thinking someone knows the answer. I have two lawnmowers with Tecumseh engines and no matter what I do I cannot get them to start using the primer bulb. But if I open the air filter, dump a little gas in they start right up and run great. I have cleaned the carbs, boughta rebuild kit for one but I still have the same problem. Won't start with priming but starts and runs fine when I put gas in the air filter. Any suggestions as to what the problem is?