Briggs FloJet Carb

I have a Briggs and Stratton flojet carburetor and I need to check on a matter. It leaks, but it may be caused by my practices. Anyhow, when I shut down a motor to put it away for the day, week, or longer, I normally kill the gas, and then feather choke the carburetor until it no longer runs and dies. The carburetor has no direct drain. Anyhow, would the practice of choking the carburetor as it runs out of gas cause excess gas to get into the air tube? Would I find gas in the canal that connects the breather tube to the carb bowl? I know I have no leak pass the emulsion tube and the needle is fine. Just need to get an opinion from you. Carburetors are the bane of my existence at times--and that is true right now.

Thanks.

http://outdoorpowerinfo.com/repairs/images/large_2_piece/whole_large_2_piece.JPG

The link is to a picture of the type of carburetor I am dealing with.

should only be fuel in the bowl.

If that is the case, then why does the rubber air tube that connects the carburetor to the block have gas in it?

NOT sure what all you've got going on, but if you want to drain the float bowl you can unscrew the main needle assembly as a unit.

Basically the same functionality as a bowl drain plug.

The breather tube goes into the side of the air horn, just under the filter, correct?

Strange that liquid fuel could make it that far up under any condition.

If you shut it off without choking or turning off the fuel, is there still gas up there?

How is the oil level? Any gas in the oil?

You mentioned a leak, where is the leak?

Hello G6 at Snook,RD

OK I'll bite! Why do you choice the engine to shut it off?

Guido.

Steve at Advance has the best idea.

If you have fuel in the breather hose, its coming from the crankcase and you probably have gas in your oil, or at least enough gasoline vapor in the crankcase that it condenses in the breather hose.

Being that style carburetor has a sintered filter in the bottom of the air horn, its not likely that it could fill up to the point the gas would go into engine while it is sitting.

Is there any chance that this engine has a pulse type fuel pump? If it does, I would check the diaphragm. A pinhole in the diaphragm allows a direct path for gas into the crankcase.

Also, your practice of choking the engine to get the last bit of gas out of the carburetor may be causing it to suck to much fuel into the cylinder and some of it is going past the rings. Gas may be going past the rings while its running anyway.

First of all, how does one post a photo on this site nowadays? I tried photobucket, but the ads just attacked me as if they were mosquitoes.

Secondly, I have found through research that the flo-jet carb had a problem with gas getting past the emulsion tube. Briggs in 1996 issued a bulletin that suggesting using a teflon washer in a certain kit. This is not a problem here because I have tested the carburetor with gas and it did not leak past the tube; I saw no fuel in the tube nor any leaks.

Next, I ran the motor--a 16hp Briggs I/C motor from the mid 1980s--and it ran like a champ, idled up, down, and so on and under load. I cut off gas, but did not feather choke the carburetor, and killed the motor as it ran out of gas. I then removed the air filter, and found fluid in the bottom of carburetor underneath the air filter tower. That surprised me. What gives?

FYI, the breather tube goes to the side of the air horn as you describe.

Tomorrow, I will run it and kill it without cutting off the gas.

I guess I am a perfectionist, but I don't like a leaking carburetor even if it is a few drops. As I said, the motor runs great with this carburetor, but it is mystery why it weeps out the welch plug and the bottom of the carburetor after you shut it down.

Opinions and advice appreciated.

TRK,

It is a gravity flow set-up. No fuel pump. Also, I have learned over the years to cut off the gas after use.

For discussion sake, would a motor run as well as it does if it has gas getting past the rings? Like I said in my latest posting, it runs like a champ. Starts easy and on from there.

I will add this, though I doubt it will matter: I have switched from 30w to Amsoil 10w-30 (both small engine) due to winter usage and my preference for synthetic.

The welch plug in the bottom, is it possible you are looking at the drain hole in the bottom of the air
intake? It's a little stone filter designed to let pooled fuel out and not let dirt in.

It is normal for an updraft carb to loose a few drops of fuel as the engine is stopping. It's just fuel
draining back down out of the intake when the engine vacuum stops, and is even worse if the engine happens
to kick backward off a compression stroke. Same thing following a failed choke assist start, some fuel will
drain back down.

The liquid you are seeing under the air filter is probably engine oil. It is common for some oil vapor to
get carried out through the vent, especially when the rings get some wear.

I doubt it I am mistaking the welch plug. On this carburetor it is pressed into side at the base of the intake tower.

Thirty year old rings probably have some wear, but this engine hasn't seen a great deal of usage, probably more abuse from neglect than wear from use.

Any chance the rings might be sticking a bit? On an 8n you can put a dab of atf or Marvel Mystery Oil in the spark plug holes and let it set. For a single cylinder motor like this? What would you suggest?

When you chock an engine to kill it, you are filling the intake manifold with gas.
Which will drain back down when the engine dies, and put gas in the air tube.

I believe if the float sticks it can suck fuel into the
tube and air cleaner. Ed Will

My model 19 Briggs drains off any extra
gas through the bottom of carb , (as others
have said ) even when hand cranking with
choke closed, maybe that drain on yours
is completely fouled with dirt , not working
at all, which would explain fuel in vent
tube, A leaking float that was filling up
with fuel was the cause of my carb dripping
gas , new floats are plastic , also check
long brass jet tube is seated and clean
and before splitting carb , that tube has
to be removed. It's under main jet
on bottom of carb. If you see corrosion
soak or spray it ,

I believe if the float sticks it can suck fuel into the
tube and air cleaner. Ed Will