Briggs & Stratton Intek no power, too rich


I have a lawnmower with a B&S 6.5HP Intek (overhead valve) engine. It's about 4 years old, and from day one it has always started on the first pull and ran with no issues. I had finished the lawn a couple of weeks ago (it ran fine), and put it away. When I took it out again for the next mowing, it was very hard to start, and it died after about 10 minutes.
The plug was all "gunked" up with carbon, unburned gas and general crud. I *thought* I saw some bits of metal on the plug, but I can't be sure. I cleaned it, and it ran again for about 5 minutes, and died again.
So, here is what I did next:
1. Opened crankcase and checked governor system (it was okay). 2. Removed float bowl from carburator and cleaned everything I could see, with carb cleaner. 3. Drained fuel tank, disposed of old fuel and bought new, fresh fuel. 4. Put in new air filter and new spark plug.
Now, the mower runs, but it still seems to be very rich. It actually runs okay if I remove the air cleaner, but once the air cleaner is on it loses power and starts loping, and is way too rich. It also backfires quite a bit through the carb.
Here is what I'm wondering:
1. Could the intake valve have fractured? If it did (say, a small piece broke off), could that make the engine run too rich? I'm wondering this because one day the engine ran fine, and the next day it was essentially "dead".
2. If the intake valve idea sounds silly, do you think it could just be that the carb has a problem? I took the carb apart (the float bowl) and cleaned everything I could, as well as I could. I'm willing to spend the $35 on a new carb, if someone who has had some experience with this thinks it may be worthwhile.
Thanks, Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@yahoo.com wrote:

Hmmm, Check the gaskets? If engine vacuum is low....... Spray WD 40 generously around gaskets if engine runs better that means air leak towards intake.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
More text inserted.
--

Christopher A. Young
You can\'t shout down a troll.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you found oil on the plug, you may have broken or worn rings. Check the compression. Did you gently blow out the fuel inlet at the carb? Also remove the jets and squirt carb cleaner into the holes they go in. Your gas container and tank can build up crap that must be rinsed out with fresh gas. Good Luck.
Stormin Mormon wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.