What are the numbers on the engine? I believe this mower was equipped with a Briggs - but I am not sure if it was the flathead or overhead valve engine. Most of the primer problems are related to a bad gasket between the air filter housing and the carburetor. The primer bulb is actually a small air pump that sends a shot of air to the carburetor float bowl. Air pressure in the float bowl forces a shot of fuel into the carburetor venturi area. Since your engine starts on a prime - but does not continue running, I suspect there is an additional problem in the carburetor. Perhaps the main fuel jet is dirty or perhaps there is old fuel in the carburetor from last year. Try giving the carburetor a little more prime to see if the engine will continue running. If the engine starts, replace the gasket between the carburetor and the air filter housing. Sometimes the plastic air filter housing warps and a gasket does not solve the air leak. Some techs use two gaskets. I usually replace the air filter housing.

Hello, folks. I hate to revive this dead horse, but I'm having the same problem described in this thread -- again. The starter on my John Deere RX-75 is refusing to turn over again, unless I happen to catch it in the right mood. It fires off fine when I walk by and flip the key in the garage. But sometimes it doesn't after I've turned off the motor -- usually with half of the yard still to cut. I've fiddled with the shift lever to make sure it's in neutral, and I've checked all the wiring that I can see. Any other ideas? When this happened last year, I tried some of the tricks mentioned here. I thought one of them must have worked, because the mower straightened up and cranked right. Last summer I took the mower to a John Deere dealer after this happened. It cranked like a new mower in the shop, of course, so I figured (hoped) they had cleared up whatever the problem was. No such luck.

Best that you test the wire at the PTO clutch connector for voltage when the PTO switch is turned on. Do this with the key on, engine NOT RUNNING. If you do not have voltage at the clutch when the PTO is turned on, your PTO switch may be bad or there could be a broken wire between the PTO switch and the PTO clutch. If you DO HAVE voltage at the PTO clutch wire connector but the PTO clutch will not engage.......your PTO clutch has likely failed. You might even get lucky and find that wire broken or unplugged.

2 things to check right off. Check for spark at the plug. You can do this by removing the spark plug, connecting the plug back to the spark cable, then lay the plug on a metal part of the engine where you can see the spark end of the plug. Watch for spark while someone sits in the seat and cranks the engine. If you do not have spark, post back stating that. If you have spark, put the plug back in and go to the next step. Remove the air cleaner and spray a burst of spray carb cleaner into the carb, or drop a couple of teaspoons of gasoline into the carb and immediately try to start the engine. If the engine runs for a second or 2, there is a problem with the fuel system not delivering fuel to the engine. DO NOT use "ether starting fluid" in a small, air cooled engine. Do this and post back.