Full of oil was running and quit i started it up on first pull welded for a few minutes then quit again now it will not start. getting fire to plug and gas to carb. i cannot figure it out, any help would be appreciated. thank, Mack

Some engines have a low oil cutoff switch. If the oil level drops to a certain point it kills the engine. Your oil level may be close enough that after starting and running for a little bit the level drops enough to kill the motor. After sitting for awhile the level rises enough to allow the engine to run again check the level and add oil if necessary.
Hope this helps.
Bob

check the tightness on the oil plug and the filter sometimes we think we get them tight enough but not for the machine

try and run it with a loose gas cap the vent could be clogged then check for spark when the engine dies or even better get a inline spark tester then you can see it when its dieing

if the plug is sooty your float is set wrong the air filter should have oil on it to catch dirt.sounds like a carb problem although it could be the power valve

check the fuel pressure regulator.

Oil on the plug is an oil problem. it means that either you tipped the mower and oil ran into the cylinder, or you put too much oil in it and it's leaking into the cylinder. Check the engine oil level, empty some if it's over the level it's supposed to be. You'll want to clean the cylinder, and here's how to do it. Get a can of starting fluid. Take the spark plug out, and remove it from the wire, spray a good 5 second shot of fluid in the cylinder, and pull the rope several hard pulls. This will shoot the fluid and oil out the spark plug hole, and the starting fluid will evaporate within a couple of minutes. Spray the firing end of the plug with starting fluid to clean, shake it out, blow on it to get the extra out, and let it dry(should take about a minute.) Pull the rope another round, and then put it back together. It should run fine after that. It'll probably smoke a decent amount at first, but it will go away within a few minutes.

Prime away... on a chainsaw it does NOT squirt fuel into carb. It draws fuel from tank, through carb, and returns it to tank.
Using the choke however will flood it in a second once it has fired. with a good fuel supply, 99.5 % of chainsaw won't start problems are flooded. Lou

You may have to take out the carb and get it cleaned / air-blown out. Looks like some little valve is stuck. Also make sure you are getting enough sparks at the plug tip. If you have left it long in a damp place it may take several pulls on the cord for the engine to fire-up and run. Try spraying some WD-40 into the cylinder through the plug-hole. Then pull the cord again. After a few pulls remove the plug again, and put like a spoonful of clean 10/30W engine oil into the cylinder, and keep pulling the cord until you see some smokes at the exhaust. If the engine fires up and run a few minutes, but stops later. The engine might be out due to incorrect oil/fuel misture.

Remove spark plug, clean and dry. Replace plug. Remove air filter. Spray WD-40 into carb opening; one second blast. Turn over engine, (pull handle). Engine should start briefly and run for 3 seconds.  If not, you are not getting spark to spark plug. If engine starts, you have a dirty carb and you can buy a rebuild kit from manufacture.

If the oil level is low it will do this, but I also know this to happen when the oil is very cold (thick) an won't fow back own o the crankcase where the oil sensor is. The slow return results in a low oil level. My solution is to start it, when it dies wait a couple of minutes and retry... after a few starts, the oil will warm up, thus flowing back down faster and it then will run. Another option is to use a thinner oil ie;5-30w.