Briggs engine flooding after shutting off

[38racing]

I assume you did static governor adjustment for each carb install? Is governor holding throttle wide open when you are about to start it?

[creia]

I assume you did static governor adjustment for each carb install? Is governor holding throttle wide open when you are about to start it?

Yes to both questions.
Michael

[creia]

UPDATE:
I had some time today so I decided to take a different tact....

I opened up the original (10 year old) Briggs carb and one of the new aftermarket carbs I bought and compared the condition of the rubber ("Viton"?) tips on the end of the respective needles. The original (10 year old) Briggs needle tip was VERY slightly tapered at the very end- just barely descernible to the naked eye. Maybe this was the cause of the carb flooding when the mower sat for a couple of days?
The needles from both carbs seemed to be identical in size and structure so I took the one from the new aftermarket carb and installed it in the original Briggs carb.

I then reinstalled the original Briggs carb in the mower and connected everything up and added fuel. The engine started and ran perfectly (with no surging) on the second pull. (Note:That in itself is no big surprise as the engine ran perfect before with the original carb (no surging)- just had the flooding problem after sitting for a couple of days) Both the automatic choke plate and the throttle plate are working perfectly. "Only time will tell" after a couple of days if it floods again.

While I had it running I checked the operating rpm= 2,950 Is that correct for one of these type of mowers? I could find no mention of engine operating rpms in the owners manual and specifications. I can see that there is a metal bracket that the governor arm spring connects to that you can bend forward or back to increase or decrease rpms.
Michael

[bgsengine]

Excellent. So you know for sure that your problem is the clone carbs didn't work. As for the RPM's , top no load on a pushmower is determined by blade tip speed - which means blade length determines what the engine RPM would be set to by the factory. (And that's usually found by the type and trim codes, but I believe only via the power portal.) However, for a 21 inch mower, 2950 sounds about right , maybe a max of 3100 would be pushing safety (Blade tip speed determines the stop time of the blade brake / deadman control... as well as the mass of the blade itself, but that's usually a case where replacement blades may often be lighter than Factory blade, so mass isn't gonna be a safety factor.) OTOH, If machine is out of warranty and you have no concern about your safety or safety features, you could of course boost the RPM higher (but higher RPM will not always improve mower performance, and it will waste gas.. which means waste of money..)

[creia]

While the results were very encouraging, I am not exactly "out of the woods" just yet...
Remember, that the (only) issue with the original Briggs carb was that after a few days it would flood the intake and would not start w/o clearing it out. I'll hold off on my jubilation until I can try starting it again after a few days.

I hope that the needle from the clone carb has a true "Viton" tip just like the OEM Briggs carb needle and not just a "regular" rubber tip that will degrade much more rapidly especially with ethanol-laden fuel. The Briggs needle lasted 10 years..
Michael

[Arkie]

I've had that same experience with Clone carbs being bad when new, especially the Nikki clones.
I've taken parts and pieces from a NEW clone carb and used them in the OEM carb or a carb that has the slight roughness IF BOTH carbs could use the same parts.
One flooding over an extended period of time can sometimes be confirmed using a Mityvac or pressure bulb tester before the carb is taken apart. I have a really good magnifier glass and can sometimes view the vitron needle tip under the magnifier and see a knats bristle on the tip.
bsengine touched on a issue I've also seen on some of the Nikki carbs that leak over a period of time and can be usually confirmed using a mityvac or pressure bulb. It's not the needle seat but the emulsion tube gasket about the needle seat is not sealing off the fuel input to the needle seat area.

I usually buy the clone carbs from Amazon so as to get FREE RETURNS including shipping, but I also have Amazon Prime so no shipping fees to me other than the $15 monthly rate for Prime.

I'm getting about a 50/50 chance of one running correctly when installing a clone on the very small 2 cycle engines, weed eaters, trimmers, leaf blowers.

Good to hear you got it going. Takes some patience when dealing with clone stuff but at least you were working on your own stuff and not wasting lots of time, effort and losing time and money installing China clone stuff on a customers equipment.

[creia]

I got curious and had anticipation....
It has been 48 hours since I last ran the mower after switching out the original/old Briggs carb needle with the new one from the clone carb. Today, The mower started and ran perfectly on the first pull!
No black smoke on startup and apparently no carb flooding (yet?) like before. I'll wait until the weekend to try starting it again. So far, it looks like a worn carb needle just might have been the culprit for the carb flooding when the mower sits for awhile- encouraging...
Michael

[KE4AVB]

Well i usually just use my mityvac tester to pressure a carburetor inverted so the float weight is on the needle valve and seat looking for pressure drop over 30-60 minutes.

[Arkie]

Well i usually just use my mityvac tester to pressure a carburetor inverted so the float weight is on the needle valve and seat looking for pressure drop over 30-60 minutes.

AMEN

[creia]

Well i usually just use my mityvac tester to pressure a carburetor inverted so the float weight is on the needle valve and seat looking for pressure drop over 30-60 minutes.

You professional techs have all the cool tools and equipment!
While lowly garage hacks like me w/o all those goodies sometimes have to resort to "get-er-done" methods....
Michael