Small Engines (Lawn Mowers, etc.): Briggs & Strattion 3.5hp throttle free with primer bulb, briggs stratton, appropriate boxes

Question
QUESTION: Hi John,

Have a Murray lawn mower bought about 8yrs ago with a 3.5hp Briggs & Stratton with throttle free carb.  It seems to be running rich to the point of coughing and dying and has only gotten worse, even with the air cleaner off (that seems to increase richness).  If I restrict air flow at the carb throat even the tiny bit, it dies all together.  Immediately soots up spark plug.

I took the tank and carb off, thinking the float valve was stuck open, but walla, this carb has no moving parts (all plastic) so I carefully cleaned everything up, cleaned out any sediment and blew out all orifices I could identify with compressed air, but to no avail.  Runs exactly the same.

I noticed that after many frustrated tries to get it started and it would barely keep running, mowed what I could.  I had only 1/4 tank of gas, and for about 1 minute before it ran totally out of gas, it quit gagging and sputtering, and ran smoothly at normal RPM.

Are these carb's throw away carbs?  Gads, with no float valve, mixture needle screws etc. not sure what's causing this carb to run so rich.  Any ideas? If you need engine model #'s etc., do let me know where to look for it/them.

Thanks!
B.L.S.


ANSWER: Hello B.L.S.:

I Suggest you Purchase a New Carburetor. The Automatic Carburetor are a Pain in the B---. If you have Cleaned the Carburetor and the Engine Runs the Same, then a New Carburetor is your Only Option here. I Really Think the Designer of this Carburetor needs to Re-Think the Design. It May Look Good on the Drawing Board, but in the Real World it Just Does Not Measure Up when it Comes to Repairing it. LOL. You can View a Breakdown/IPL of the Unit at this Site Addy; http://www.briggsandstratton.com/maint_repair/manual_and_more/doclist.aspx?categ and Enter the Model Numbers (XXXXXX) and Type Numbers (XXXX) in the Appropriate Boxes and Click GO. Then Select Download PDF. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John

---------- FOLLOW-UP ----------

QUESTION: Hi John,

Thanks for the very concise feedback.  Do you know if those plastic automatic carbs can be soakeed overnight in regular carburator cleaner (at this point only tried to blow out all orfices with compressed air), about how much those carbs are, and where to get them (I don't seem to find much on the net about them at all) and where the Model & type #'s are located on those engines?

Thanks!
B.L.S.


Answer
Hello Again B.L.S.:

The Model Numbers are Usually Stamped into the Blower Housing (metal engine cover) Across from the Spark Plug. You can Soak the Carbuertor in Carburetor Cleaner and it Usually Does Not Damage the Carburetor Housing. You can Purchase the Carburetors from your Local Small Engine Service Center or Online from Outdoor Distributors @ http://www.outdoordistributors.com/ , Phone 1-877-707-2787. The Cost was Around $30.00us But it has been a 2 Years Since I Purchased One. If you Hit a Snag or this Does Not Correct the Problem,  I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.

Respectfully

John