Briggs engine flooding after shutting off

[creia]

Troy - Built 21" walk behind mower
Briggs 550EX Series 140cc
Model # 09P702-0005-F1
DOM Sep 28 12
This is my personal home lawnmower that I purchased back in 2012. (Yes, I know it is an "El Cheapo" low quality Lowes mower! ) That being said, it has actually served me (surprisingly) well until very recently. The last few times I went to use it it was very hard to start. I had to do repeated pulls on the starter cord (Today 15 times) only to have it keep sputtering and stop until it finally started then spewed black smoke. Once it gets up and running it does fine the rest of the day. No more black smoke and starts up and runs fine every time on the day I am using it. I pulled the spark plug and it was black (rich) and wet with fuel. Even the bottom of the air cleaner filter element was partially wet with fuel. It seems that once I shut it off and do not use it for a week or so fuel is leaking into and flooding the carb and sparkplug. That sounds like it could be a needle/seat and/or float problem to me? What do you all think? This is the newest small engine I have ever worked on- most of my "patients" are 50-60 years old!

Here is my question:
Briggs sells a carb "rebuild kit"for $ 28.00 or a new carb for $ 48.00. Orrrrrrrrr..... I can buy an after-market (China-made)entire carb for anywhere from $10-22, with free shipping on eBay. Before I take anything apart to inspect or purchase anything, what would you pros recommend?
Thank you as always,
Michael ****EDIT:(More information) I just had the mower off for about 2 hours and went to start it- It fired right up with no black smoke or sputtering. What ever is causing the condition I described must take awhile.

[KE4AVB]

Needle probably leaky over time.

As for the carb repair kit here on off the eBay that you might try.

https://www.ebay.com/itm/174103566958?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=174103566958&targetid=1496860706532&device=c&mktype=pla&googleloc=9013259&poi=&campaignid=19851828444&mkgroupid=145880009014&rlsatarget=pla-1496860706532&abcId=9307249&merchantid=6331574

[bgsengine]

if it is one of those plastic body float carbs, also check the main venturi (which you won't really notice a problem until you remove the main nozzle assembly) they DID have some issues with the venturi (non-replaceable) separating from the body rendering the carburetor useless (I have done a couple warrantys for that) However if it ends up being just a seeping needle/seat (they will over time, obviously as the seat material degrades and hardens) I'd probably just throw a new carb on it (they are easy to replace, more difficult to rebuild) and if you get one of those $10 china carbs , but 2 or 3 and keep the spares handy in a COOL DRY place (50 degrees-ish, low humidity would be ideal) they can last for a couple years (or more) and if all 3 are "good" , then your carb supply will outlast your lawnmower most likely. Or you can spring for a new OEM carb (Again , easier to just pop the old one off, put new one on and away you go) then save back the old carb to "tear down" and try and learn from it (they had problems with the main nozzles too , I believe there's a TSB in briggs portal for that issue) o-rings can be finicky as can R&R of the main nozzle assembly , and as mentioned once you remove main nozzle assembly , check if the Venturi wants to fall out or wiggle (loose) and if it does, the carb is trash. Really isn't much replaceable on them (plus it can be hard to put the float seat in the body properly to full depth without damage, Briggs breaker plunger bushing driver tool though is the perfect size and shoulder depth to do the job, provided you can get the seat to even start in square - it fits loose in the upper part so it can spin around and go in the wrong way if you try and just drop it in place... After the first few I wasted time fixing, I found it was simply far faster (and thus cheaper to the customer due to labor time factor) to just swap out the carb for a new one. ($35 labor $15 parts = $50 or $32 carburetor and $10 labor = $42 - Note that was "back then" pricing pre-2020...)

[KE4AVB]

OEM carb now lists for $45.40.

DSB-1060 which where they made a change because the jets were gumming up. They move so they are submerged in the fuel.

It is available in the downloads here under Briggs for reading and reference.

The only real problem I have seen with these is the fuel jelly and jelly beans. Usually just a simple cleaning.

[38racing]

Any room to add a shutoff valve? Just had a couple powermores by mtd. No room. Thought I could use a rght ange like tecumseh snowblower but they prevented that by putting output nipple o a slight angle forward.

[bgsengine]

Any room to add a shutoff valve? Just had a couple powermores by mtd. No room. Thought I could use a rght ange like tecumseh snowblower but they prevented that by putting output nipple o a slight angle forward.

Could do what I do with my Columbia tractor - get yourself a hemostat with enough reach and use that to pinch off the fuel line when unit is going to sit more than a few hours. My tractor don't have space really to locate an easy access shutoff so I just pinch off the hose when done for the day. Only caveat is you likely will want to replace fuel lines once a year or so (I pinch off mine ahead of the fuel filter so I don't worry too much about it, but still replace fuel lines every couple years, whether they look like they need it or not)

[creia]

Many thanks to all who replied- very much appreciated
With all things considered and everything I have learned from your replies, for right now, I'm going to try one of the cheap clone carbs (Found a couple on eBay for $10.00 and free shipping) and replace the OEM carb. I will report back with my results. Got to thinking- Aren't a lot of Briggs parts being made in China now? Maybe this aftermarket carb is made in the same factory (and specifications) as the Briggs-branded OEM carb?
To 38 racing: That is a good idea, however, I do not think there is any room.
Michael

[creia]

UPDATE: (FINALLY!!)
Just today I swapped out the OEM Briggs carb with the aftermarket carb I purchased on eBay. The process went very smoothly as I found an excellent video on YouTube that helped with the removal of the old carb.
https://www.youtube.com/watch?v=a7ANgJKJ8_g

All went well with the carb install until I went to run it...
It would not start so I gave it a little shot of starting fluid. It started, however, it would surge (BIG surges) about 20 times then it would run great (full constant RPM) for about 20 seconds, then repeats the process over and over. If I shut it off it will not start w/o using starting fluid, then it will resume the surging and running sequence like before.
Does anybody have an idea what is going on and/or what to check? Maybe I just got a bad carb? (only cost $ 10.00 including shipping)
Thanks for any help.
Michael

[bgsengine]

Bad carb would be my first guess - However, check for any air leakages (do the o-ring and retainer for the intake fit nice and tight?) but rather than waste time on likely bad carb, get another 10 buck carb and see if it solves (or changes) the issue. Also wanna be sure you got the air box on properly and not restricting any air bleeds. Also try blocking off the little white nipple (it's a metered vent that on some models connects to an EVAP system) if it runs better (and/or starts by itself without starting fluid) then it is likely that little vent causing your issue. (I plugged off one of them with an automotive vacuum cap on one engine, and it worked fine ever since) Also is it prime start, choke start (manual or thermostatic), or what? (Carbs may have variations - but aftermarket carbs may be a "will fit" universal type, which might factor into the equation) Finally if you do swap out carb and new carb runs fine, pop your old ones apart and pop out the center nozzle, then check if the venturi is secure (and no gaps showing) as those venturis can separate if they were not correctly assembled at factory (shaken apart during shipping?) - they're not serviceable so if venturi leaks, whole carb is trash.

[creia]

Thank you Brian,
As to the type of choke...
It does not have a primer bulb nor does it have a manual choke (lever or knob), so I guess it must be a thermostatic? Is that mechanism built into the carb and as such not visible? (Never had an engine with a thermostatic carb before). I have to tell you- This aftermarket carb is absolutely IDENTICAL in appearance to the OEM Briggs carb!
Michael