Small Engines (Lawn Mowers, etc.): B&S Quantum, quantum model, cylinder compression

Question
Model 12M902 engine on my lawnmower.  I had problems starting the mower.  It would run a few seconds and die.  I tried cleaning the carb - nohelp.   I purchased a brand new carb and it does the same thing.  If I hold what I believe is the throttle bar(opening the valve in the carb), it will run at high RPMs until I let go, then it dies.  I don't know what to do now.

Thanks in advance.

Answer
Hello David:

Is the Intake Gaskets Sealing Good. If the Gaskets are Pulling Air the Engine Will Not Idle. Check the Cylinder Compression. Turn the Engine Quickly in Reverse Rotation of Engine Operation. If the Engine KICKS BACK, then According to Briggs the Compression is Good. Other than Low Compression and Leaking Intake Gaskets; I can't Think of Anything that Would Cause this Problem. You Should be Able to Locate a Breakdown/IPL of the Engine At this Addy, http://shop.briggsandstratton.com/BShopProductListingPage.asp?rsvp=0&PARENTID=0&... Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

Good Luck

Respectfully

John