18hp B&S carb issue

[GREASEMONKEY]

I can't seem to solve this carb issue.
01 Argo big foot 18hp B&S
My argo sat in the shop for nearly a year. I changed the oil, flushed the fuel tank, and rebuilt the carb. As I was adjusting the carb I found that it was blowing fuel back at full throttle.
Here's a video of what I'm talking about.

https://s1097.photobucket.com/albums/g348/GREASEMONKEYSC/Argo/?action=view&current=20130922_172442.mp4

[Toys4Me]

My 16hp B&S was doing that when the jets were clogged and the bowl was dirty. I would pull the jets and emulsion tube and blow some carb cleaner through just to make sure they are clear.

[GREASEMONKEY]

Carb is a fresh rebuild. Internal's are hospital clean!

[Nubs]

I would bottle feed it to eliminate any questions about water in the fuel etc, we have trouble with reformulated gas when it sit for a few months.

[blown84gt]

Ethenol or 100% real gas?

[Nubs]

its a 10% mix up here.

[Tomo]

hi ,
do tappet [valve clearance]
do a compression test wet and dry
Even though it has a decompression system the readings should be within 10 % of each other and at least 120psi
Yes it may look to be fine
Must do a leak down test [eg 100psi air pressure and listen for difference between the cylinders ]
The gage will also have a green zone ,the needle must be within that area
Use of percentages is different from gage to gage
Using a snap on leak down no greater than under 3% great, but no more than 5%
The briggs twin vanny has a poor [not wide enough and definitely not much support from piston ]top ring
The twin vanny engines run poorly when the hone marks disappear eg degraded by age etc
ps do a compression wet test after leaK down
A wet test is 2-3 squirts of oil in cylinder and this seals the rings up if worn out

tomo

[GREASEMONKEY]

Fuel is fresh, I'll check comp. But I doubt that's gonna be it. There's only 120hrs on my machine!
Nope, don't get much time to play!

[JohnF]

It looks like the fuel is bouncing off of the choke - sort of squirted from the side and at the butterfly valve. There should be some sort of nozzle that injects the fuel mid stream. Of course the camera view might hide what's really happening. I am wondering if there is a pinched/cut/worn out gasket between the carburetor body and cover.

But, I've never even seen one of these carburetors except in you pictures.

Be careful - that atomized fuel being shot into the air is a fireball if given a source of ignition.

[MAX IV Mark]

A plugged exhaust will cause fuel spitting out of the carb at full throttle. But it would be even and continuous, and your video looks and sounds like an intermittent misfire. Looks like it is firing when the intake valve is open. I think I would look for bad ground connections or a bad coil, or ignition module after that. Tomo mentioned to check the valves, a sticky valve could cause it too.

[Toys4Me]

I was just thinking along the lines of MAX IV Mark. Are you sure both plugs are firing?

[GREASEMONKEY]

Sorry guys. I got insane busy in other app with customer jobs, so my toys had to take a back seat.
I'll be on it again in a few days, and hope to have a solution.

[GREASEMONKEY]

Finally got back to the Argo repairs. I adjusted the valves, tweaked the governor, and tried adjusting the carb again.
Still having the same issue!
Here's what I've been trying to fix all along.
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It dies as soon as you romp the throttle, and if you baby it up the rpm range it spits fuel at high rpm.
I'm lost. .........
Fresh carb rebuild, New plugs, check valves, check spark, fresh fuel.

[Nubs]

acts like there's a vacuum leak or the compression release balls in the cam are stuck. rare but does happen.

[GREASEMONKEY]

Yeah I was kinda starting to think it was internal.
Guess it's time to pull it, and mount it to the work bench so I can start digging deeper.