Had the same trouble. Should be a adj screw on the carb. Count the number of turns "IN" until it stops. Remember that amount. Now remove that screw, spray Gumout in that hole and in the carb throat. Replace screw to where it was. Do not install (dirty?) air filter yet. Try starting it.

should be a solenoid valve on the carb that works with your safety systems. doesnt allow fuel through the carb

is the line from the tank letting gas to the carb?

The gas is getting to the carburetor

is there a gas shut off valve you may have forgotten about?

It starts when I spray starter fluid in air intake, I've changed spark plugs, fuel filter, gas, cleaned carb, replace needle seat still no luck! Like I said it starts for a second when using starter fluid or gas in spark plug hole but once that burns out it shuts off!

Murray 12.5hp 40508x92

Briggs and Straton 28R707

Please help!