I really only have one problem with this lawnmower engine. The Engine is on a 21" Murray Lawnmower which is about ten or twelve years old i think. The problem I am having is that the engine will not stay running. The throttle is working fine and there is spark. I recently cleaned the carb and magneto contacts, and if I use starting fluid it will fire up right away but sputter out right away. If i keep spraying the engine will stay running, but it will not start or keep running on clean gas. Any ideas would be great. Also the spark plug and filter are both new and i am using new gas. The line to the carb is clear and the float is filling with fuel, but after that point i don't know if fuel is making it to the cylinder. I was wondering if I have a compression problem and if so how would i know and how would i fix it.

check the diaphram, and no compression is not the case. if it starts off of starting fluid that means that it has enough comppression. are you sure ya hooked everything back? if you can, pictures or model numbers can help alotl.

It's probably not a compression issue since it will start with a prime. You most likely still have a carburetor problem. Maybe if you could post a picture someone would be able to identify the engine and tell you things to look at.

Don't worry looking for any diaphragms if you have a float carburetor there should be no diaphragms unless there is a fuel pump.