I know next to nothing about my lawn mower other than that I don't want to pay $70 to fix a $120 machine :)

Anyway, I have a B&S 5.5 mower (120000 series?). It has had trouble running since I got it out of the garage this spring. It would splutter and die after after half a minute or so, though I could run it for a couple of minute if I pressed the primer bulb 20+ times (rather than the recommended 3 times).

The problem has gotten worse so that now it does not run at all unless I continuously prime it (which makes cutting the grass difficult).

Is this a symptom of a specific problem? (And hopefully one I can fix here at home). I've put in a new air filter, sparkplug, and fresh gas. The oil level looks fine. From what I've read on here I'm thinking that cleaning the carbeurator is next on the list. But I'm not sure how to take that off so I figured I would ask first.

Any help will be much appreciated!

Yup, most likely you've got a dirty carburetor. Ideally, to do a good job of cleaning the carb, you need carburetor cleaner and compressed air.
To start, if there is no fuel shutoff, you'll have to pinch the fuel line that comes out of the gas tank, anywhere before it goes into the carburetor. Then remove the bolt at the bottom of the fuel bowl. It should be a 7/16 size, if I remember correctly. Have a small container underneath, if there is room, to catch the fuel. Then carefully pull the bowl off, take care not to tear the gasket. See if there is water and dirt at the bottom of the bowl. Clean it thoroughly with a rag. Then, if you have carb cleaner spray, spray up all the openings in the carb. Use a fine wire to poke up the holes. Then, you need compressed air to spray to the holes, to remove the dirt loosened by the carb cleaner. Then take the bolt (also the jet) that held the fuel bowl onto the carb, and poke a fine wire through the small holes in the sides, making sure they are not plugged. (I use tag wire). Blow them out with air. Those tiny holes plug up easily. Then just assemble everything back together.
I hope I didn't miss anything.

Thanks, I've run through most of those steps now - it 'looked' clean inside. I don't think I can clean the real innards of the carb unless I take it off of the mower - which looks like a fair bit of work. Is removing the carb usually necessary to clean it?

I would be nice, it's really not that bad, just remember all linkage spots, and uses a digital camera if you have one.

Looked clean and clogged up is different. You can't see the clogs. Its not too hard to take it off. Be sure on your linkage and tear it apart and soak it in carb cleaner and blow it out with carb cleaner through any holes you see (compressed air also if you have it) a camera taking pics along the way is good for reference. I'd also go get a carb gasket kit, have the numbers off the engine and go to a small engine shop, they should get you what you need.

I just wanted to stop back in a say thanks for the help. I followed the suggestions and got my mower going again. I, and my neighbors, thank you. :thumbsup: