It's a briggs stratton small lawn mower. It was given to me and I put a new spark plug in it and cleaned the filter and it cranked right up. I used it 3 times and it died again so I got a nother spark plug because old one was rusted and changed oil and filter is clean and has gas in it... it starts for a second and dies. Why won't it start?

Sounds like it needs the carb cleaned.

It could need a new diaphraphm for the carb.
YouTube - How To Replace The Diaphragm On Briggs And Stratton Primer Plastic Carburators On Metal Gas Tanks (http://www.youtube.com/watch?v=C5nzigcNTwo&feature=related)

Thanks for that, pattyg. I have exactly that engine assembly, though it's a weedeater mower.. anyrate, I'm reconditioning it this weekend and though I have never worked on small engines before, I am mechanically inclined and that video opened my mind a bit, like a glimpse into what I should expect to find.

Thanks again

thanks for that, pattyg. i have exactly that engine assembly, though it's a weedeater mower.. anyrate, im reconditioning it this weekend and though i have never worked on small engines before, i am mechanically inclined and that video opened my mind a bit, like a glimpse into what i should expect to find.

thanks again
It doesn't matter what brand of mower as much as the engine. I fixed my murray with a briggs and stratton mower. It needed a new diaphrapm and intake tube. Take pictures before you tear it apart.

Check the coil under the engine casing remove the 4 bolts 3/8 socket and use a 1/4 or a 5/16 socket for the coil remove it clean it with a sand paper and the fly wheel make sure that it is pretty clean and then reinstall it

Here is a troubleshooting guide for you:
Notes on the Troubleshooting and Repair of small Gasoline Engines and Rotary Lawn Mowers (http://www.repairfaq.org/samnew/lmfaq.htm)
How To Fix A Briggs And Stratton Lawn Mower (Part 1) (Lifestyle & Home: DIY & Interiors) (http://www.videojug.com/webvideo/how-to-fix-a-briggs-and-stratton-lawn-mower-part-1)