If you are having trouble keeping your lawn mower started this may be helpful for you. If you are able to start your mower and then it seems that it slows down and then up and then down I may have an answerer for you. 1) On your engine there is a silver cup that is under the carburetor at the bottom of this cup there is a bolt usually made of brass. Find this nut. 2) Drain your mower of Gas. 3) Loosen the nut off and look and see what comes out it could be your mower has water in the cup if water comes out loosen the nut completely and then dump the water out of the cup. Be careful not to rip the gasket around the cup and around the nut. 4) This is a very important step Take a bread tie that comes on a loaf of bread and remove the skin on the outside of it. 5) When you look at the brass Nut you will see that it has 3 holes in it these holes must be clean for your mower to work properly. Take the bread tie and clean out the holes in the nut. 6) After cleaning out the cup and the nut put your mower back together and prime the carb. Your mower should start now and the problem should be relieved. 7) At the end of the mowing season remember to run your mower out of gas and loosen the nut once again to remove any gas left in the cup this will keep the gas in the mower from going bad as it will not have any in it. The next season fill with gas prime and your mower should run great. I have also heard of people putting oil in the gas tank and then pulling the sting a couple of times to keep the parts lubed through the winter. I have never tried the oil thing but i always run my mower until the gas is gone and drain the cup every year and this works fine. It keeps the carb. from becoming varnished over and doesn't allow bad gas for the next year. This could save you a few Dollars next year.