11 hp briggs and stratton engine blows gas back through carburetor Valve clearances are 0.005''

There are Craftman model numbers and there are Briggs and Stratton model numbers. Here are ALL the Briggs and Stratton model numbers. You numbers don't fit, but if you can find it, these repair manuals are free to download.

https://www.briggsandstratton.com/content/dam/briggsandstratton/na/en_us/Files/FAQs/model_vs_repair_manual2.pdf

This states each engine is different!

What is the valve clearance on a 21 HP Briggs and Stratton
If it turns out that the engine is a 33M677/0149-B1, the required valve clearances are 0.003-0.005" for both intake and exhaust, but this is different for each different engine size, so let's make sure we are talking about the right engine.
Aug. 27, 2014

Briggs & Stratton 21hp - OutdoorKing Repair Forum

The fuel flow solenoid or needle valve it controls may be bad/need adjusted/need cleaning. If your engine has one, it is on the bottom of the fuel bowl on the carburetor. It will have a wire running to it, and when you turn on the key, it will make a tiny "click". If you take it off and remove the fuel bowl. and clean it, then put it back on, it may solve your problem.

Briggs and Stratton Valve Clearances

outdoorpowerinfo.com/engine_specs/briggs_valve_gaps.asp

Briggs & Stratton Intake and Exhaust Valve Clearances. Model Series, Engine Type, Intake Valve Clearance ( in. ) Exhaust Valve Clearance ( in. ).

Briggs and Stratton 10hp Generator Carburetor Repair ...

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https://www.youtube.com/watch?v=O-fROtibEvE
Jun 5, 2010 - Uploaded by IFIXIT4U
In this video I will show you how to clean the carb on a Briggs10hp. This is a Nikki carb.

VERIFY your engine model numbers
Briggs & Stratton Intek V-Twin
Engine Model Numbers 407777 and 44P777
Cylinders 2 (Dual cylinder)

ITEM N m (Newton metres) lb-in Spark Plug Torque 20 180 Back Plate (to cylinder) 11 100 Blower Housing Screws 9 80 Breather Screws 6 55 Carburetor to Manifold 7 65 Cylinder Head Bolts 25 220 Cylinder Shield 7 65 Crankcase Cover 23 200 Engine Mounting Bolts 48 35 lb-ft Electric Clutch Mounting Bolt 75 55 lb-ft Exhaust Manifold 16 140 Fan Retainer Bolts 16 140 Flywheel Nut 203 150 lb-ft Armature Mounting Screws 3 25 Intake Manifold Bolts 9 80 Rocker Arm Adjustment Lock Nut 7 62 Rocker Support Screws 11.3 100 Valve Cover Cap Screws 11 100 Carburetor to Intake 7 65 Valve Clearance (Cold) 0.10-0.13 mm (0.004-0.005 in)
WARNING: Uneven tightening will warp the head. Tighten Cylinder Head Bolts down evenly by hand. Then using torque wrench tighten in sequence, in 9 N m (80 lb-in) increments to 25 N m (220 lb-in).
Intake valve push rods are aluminum.
Exhaust valve push rods are steel.
DO NOT interchange push rods.

Removal and Re-installation sequence for bolt removal and tightening.

Cold engine adjust the valve lash to 5 thousands (.005) for both exhaust and intake valves.

This would be caused by a sticky needle valve on the float in the carburetor.You have three cures 1. remove and clean the carburetor internally. 2. replace the carburetor with a new one. 3. or most simply buy and install a fuel shut off valve and turn it off when not in use. make sure you change the oil 1 4 ID LINE GAS FUEL SHUT OFF VALVE TECUMSEH BRIGGS

see if the oils coming out of the rubber hose by the air cleaner ,if it is it could be the pcv valve the rubber hose is connected to. order could be too much oil in the engine, sometimes the carburetor will flood the crankcase with gas , you have to rebuild the carburetor and change the oil.

You could first try resetting the valve clearances. The B & S Website should provide the settings as well as a manual.

The solenoid on carb was bad causing reduced gas to motor and low power

This Briggs & Stratton chart will answer your question. http://www4.briggsandstratton.com/miscpdfs/RNT/Engine%20Specifications%20Chart_ms3992.pdf