Briggs 22hp Surging Badly

[Shootertexas]

On going Surging issue. I have a 44N677-0005-G1 with a 594207 carburetor. It belongs to friend of mine.
It had an issue a few weeks ago with the solenoid not work and not allowing the engine to start. Once it was freed it ran great. Fast forward 2 weeks and running it to mow about 2 acres he calls and says it runs very poorly. Come to find out the needle was allowing gas to flood the cylinders. Brought it my house, pulled the plugs and changed the oil & filter as it was contaminated. Immediately started it and it ran fine. Removed the carb and cleaned it. Replaced the float, needle, main jet, bowl gasket and fuel pump and vacuum line.

It is no longer flooding the cylinders as I preformed a pressure test with a thumb pump and it held 7 psi.

Now the problem, while it will start, it surges wildly at all speeds until I push the throttle up to choke it ever so slightly at which point it runs smoothly. Any more choke and it bogs down. I have removed and replaced it several times and cleaned all the orifices i can see multiple times. The emulsion tube orifices are clear.

Any ideas of what to do ???

 

[Scrubcadet10]

Is your float sitting level? turn it upside down with bowl off, you want the float bottom LEVEL or SLIGHTLY down.
also did you replace carb gaskets/intake gaskets? if one is ripped or cracked it can suck air in and cause surging.

 

[Shootertexas]

I have never taken the intake manifold off the carburetor. The "plastic" seals on the intake manifold to the head look good.
The carburetor to bowl gasket was replaced with B&S part.

The float level I will have to check, but I belive it is sitting in the correct position.

Is there an idle circuit on this carb?

 

[Shootertexas]

I was told by a briggs guy here in town there were no orifices to clean and nothing to gain by removing the intake manifold from the carb. True or not?

The only piece I did not change in the carb was the plastic piece that hold the main jet.

How far does the main jet fit into the plastic piece? I push on it until I thought it was seated correclty but looking at some youtube videos, theirs appear to push in further.

 

[ILENGINE]

The jet normally sets right at the bottom of the plastic piece flush. I don't think you would get it together if it wasn't fitting correctly.

 

[Shootertexas]

The jet normally sets right at the bottom of the plastic piece flush. I don't think you would get it together if it wasn't fitting correctly.

I must have a non-normal carburetor or I'm not pushing hard enough on it.

The jet feels like it seats in the plastic tower but when you tune it over instead of the jet being all the way at the bottom it actual sits about 1/2 inch below the bottom of the plastic piece.

When I run a drill bit down the inside of the "tower" it feels like there is a ridge in it about where the jet seats.

Any ideas?

 

[Shootertexas]

This is not the carb I'm working on but is a close representation. Does anyone know what the function is of these 2 ports?

 

[ILENGINE]

Air bleed to mix air with the fuel to start the atomization process.

 

[ILENGINE]

I must have a non-normal carburetor or I'm not pushing hard enough on it.

The jet feels like it seats in the plastic tower but when you tune it over instead of the jet being all the way at the bottom it actual sits about 1/2 inch below the bottom of the plastic piece.

When I run a drill bit down the inside of the "tower" it feels like there is a ridge in it about where the jet seats.

Any ideas?

Could you post a picture of it so we can we what you are looking at.

 

[bertsmobile1]

I was told by a briggs guy here in town there were no orifices to clean and nothing to gain by removing the intake manifold from the carb. True or not?

The only piece I did not change in the carb was the plastic piece that hold the main jet.

How far does the main jet fit into the plastic piece? I push on it until I thought it was seated correclty but looking at some youtube videos, theirs appear to push in further.

The plastic manifolds are prone to warping & leaking
The O rings need to be replaced as they flatten out allowing air to leak in.
In my shop they get changed without question as do all of the gaskets.
If it comes in the rebuild kit it gets used. No value in having a drawer full of 1/2 used kits & lots to loose having to do the job twice.
If possible I try to replace the plastic manifold with a metal one,
Not only does the metal one not warp it also gets hot so aids the vapourizaion of the fuel .
The carbs are designed to be cheap to make & fit not to run a long time with minimal servicing.

The first thing you do with a surging carb is to remove the blower housing so you get clean access to the engine
Start the engine, engage the blades to put a load on the engine then saturate the entire manifold area with WD40 from a trigger pack ( not a spray can )
While doing this you work the governor so the engine runs at high revs the let it drop back to normal revs to create a high manifold vacuum.
If the engine runs silly or you get clouds of white smoke from the WD 40 burning then you have a manifold leak.
You need to work the governor if you get no response initally because there is 5/8 of SFA manifold vacuum when the engine has no load running on high idle .
And don't overlook the butterfly shaft because they can & do wear, flog out oval and leak air.