Push mower is running poorly and created excessive grey smoke. Checked and cleaned spark plug. Removed and reinstalled carburetor after adjusting float and needle. Checked fuel, is clean and water free. Mower running without smoke now but still not running 100%

Yes, black smoke is too rich, blue is oil and white is steam/condensation.

Surging is normally caused by air entering the inlet manifold or governor.

All Carburetors have adjustment
Needle height
Main Jet size
Idle Jet air control (often hidden under a silver disc).

surging

https://www.google.com/search?q=18hp+Briggs+and+Stratton+surging

Carburetor adjustment

https://www.google.com/search?q=18+hp+briggs+and+stratton+carburetor+adjustment

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Since you put it on its side, you most likely dumped all the oil from the crank area to the cylinder and carburetor. What you need to do is check engine oil to be sure it is full. Then take air filter off, clean the carburetor with carb cleaner. Remove spark plug, clean spark plug with carb cleaner. Pull the cord about a dozen times WITH THE SPARK Plug removed. Then install spark plug and try to start.

I had possibly the same problem with my lawn tractor about a month ago... I tried removing the carburetor and cleaning it, but I always ended up pushing debris into another area and creating new problems. Eventually I just bought a new carburetor, changed the oil (some gas had gotten into my oil thanks to the problems I had with my carburetor), cleaned the spark plug, emptied the oil filter and replaced it, checked the air filter ((no oil there, phew)... and it seems to be running fine after 3 engine hours (knock on wood).

My backstory is the lawn tractor was sitting in the garage with our car for two years and not used. I prepped it for long term storage, but failed to drain the carburetor of old gas, so the old gas gummed up the works (even with fuel stabilizer). When I did get it running (after changing everything listed above) a lot of smelly white smoke kept coming out, but as I let it idle in fast speed the engine strokes became more regular and the bouts of white smoke became fewer and shorter until the smoke stopped altogether.

Hopefully this helps!

Look to see if there is rust on the coli packs

SOUNDS LIKE THE OIL HAS FLODDED THE SPARK PLUG. REMOVE THE SPARK PLUG AND CLEAN IT USEING A WIRE BRUSH AND SOME BREAK PARTS CLEANER. THEN DROP SOME OF THE OIL OUT. YOU MAY HAVE PUT TOO MUCH IN THE ENGINE. THE SMOKING WAS CAUSED BY THE OIL BEEING BURNED BY THE SPARK PLUG. SOME HOW OIL GOT IN THERE. TRY CLEANING THE INSIDE OF THE SPARK PLUG OPENING WITH SOME CARB CLEANER. PUT THE SPARK PLUG BACK IN AND TRY TO START IT. REMEMBER IF THE SPARK PLUG IS FOULED UP, IT WILL RUN POORLY OR NOT AT ALL.

Yes it is a carburetor problem. The float and needle are stuck open and it is flooding fuel into the crankcase. That is why your oil smells like gas and you have gray smoke. I will bet that it is hard to determine the exact oil level on the dipstick.

First, do not run the engine until corrected or you risk engine damage. The fuel in the oil acts like a thinner destroying the lubrication properties of the oil.

Second, take the carburetor off and clean/rebuild it. When you are satisfied with the carburetor, including the operation of the float and needle, reinstall.

Third, change the oil, for the reason stated in the first.

Fourth, with fuel in tank, note level to make sure not changing by draining through the carburetor.

Fifth, remove the spark plug and turn the engine over a few times to get oil back to the surfaces that need lubricated on startup. Reinstall spark plug

Sixth, check fuel tank level for drop, if no drop, Try starting the engine.

I hope this helps you get it going.

This is what a "General service" looks like at www.arcolawn.com

• (Mower 2 cycle GS)

GENERAL SERVICE:
1. SHARPENED & BALANCED BLADE
2. REMOVED BLOWER HOUSING & CLEANED COOLING FINS
3. REPLACED SPARK PLUG
4. FLUSHED FUEL SYSTEM
5. CLEANED CARBURETOR HOUSING
6. LUBED CABLES
7. CHECKED OIL SEALS
8. SERVICED AIR FILTER
9. CLEANED EXHAUST PORTS
10. TESTRAN & ADJUSTED.

• (Mower 4 cycle gs)

GENERAL SERVICE 1. SHARPENED & BALANCED BLADE 2. REMOVED BLOWER HOUSING & CLEANED COOLING FINS 3. REPLACED SPARK PLUG 4. CHANGED OIL 5. FLUSHED FUEL SYSTEM 6. CLEANED CARBURETOR 7. LUBED CABLES 8. CHECKED OIL SEALS 9. SERVICED AIR FILTER 10. TEST RAN & ADJUSTED.

• (rider tuneup)

Tune up
1.TIGHTENED ENGINE MOUNTING BOLTS
2. INSPECTED BOTTOMOIL SEAL.
3.TEST GOVERNOR OPERATION & ADJUSTEDRPM'S.
4.CHECK SHAFT BEARING.
5.REMOVED BLOWER HOUSING &CLEANED COOLING SYSTEM.
6. REPLACED SPARK PLUG
7.CHANGED OIL.
8.REPLACED OR CLEANED AIR FILTER.
9.ADJUST FUEL/AIR MIXTURE & SPEED LIMIT SCREWS.
10.REPLACED FUEL FILTERS AS REQUIRED.
11.CHECK FUELLINES, VALVES, & CLAMPS.
12.INSTALL FRESH FUEL IN GASTANK.
13.SHARPEN BLADE(S) & CLEAN UNDER BLADE COVER.
14.CHECK DECK, EXAMINE BELTS, PULLEYS.
15. EXAMINETRANSMISSION/DIFFERENTIAL FLUID LEVELS,
16.CHECKGREASE FITTINGS, WHEELS, WHEEL BEARINGS, HEIGHTADJUSTER.
17. CHECK CABLES & CONTROLS ADJUST BRAKE &CLUTCH.
18. CHARGE & TEST BATTERY. (IF EQUIPPED).
19. TESTSAFETY SYSTEMS.
20.REMOVED CYLINDER HEAD & CHECKEDCYLINDER FOR WEAR/DAMAGE. CHECKED ROD BEARINGPLAY. 21.CHECKED VALVES FOR PITTING, WARPING, CARBONBUILDUP & SEATING.
22.CHECKED VALVE STEM CLEARANCESFOR EXCESSIVE WEAR.
23.CLEANED CARBON BUILDUP FROMCOMBUSTION CHAMBER.
24.MACHINED HEAD FLAT.
25.CHECKEDTIMING KEY FOR DAMAGE.
26.CLEANED OR REPLACED POINTSAND CONDENSER (AS NEEDED).
27. SET TIMING. ADJUSTEDMAGNETO AIR GAP.
28.CHECKED THROTTLE SHAFT FOREXCESSIVE WEAR & REPLACED IF NEEDED.
29.DISASSEMBLED& CLEANED CARBURETOR. REPLACED DIAPHRAGM, NEEDLE &SEAT, NEEDLE VALVES ETC. AS NEEDED.(see carburetor section)



I hope this helps! get parts for the service at a dealer like www.arcolawn.com

Your piston cylinder is partially full of oil and/or gas. Take the spark plug out and pull the rope four or five times to blow everything out of the cylinder. If it's still hard to pull over with the plug out check the oil level in the crank case to see if it filled with gas while the mower was on its side. Make sure the plug is dry and clean and reinstall it. When it starts it's going to smoke a lot until it cleans out the cylinder.

white / grey smoke indicates too rich mixture fuel.

lean carb, adjust float, make sure choke is off.

The primer bulb might be damaged, or the carburator diaphram could have been damaged if carburater cleaner was used.