Engine will not start (6hp model 122H02-0220-B1)

S

stans78

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Briggs & Stratton 6hp model 122H02-0220-B1

Mower sat unused for about 3 years. When I tried to start it, it wouldn't start despite many pulls of the cord.
I replaced the gas in the tank with fresh gas and tried again, to no avail. After spraying carburetor cleaner into the carb fuel inlet and many cord pulls, it started and ran for a minute or so (probably burning cleaner fluid). The mower then died and would not restart. I replaced the carb, but the problem persists--will not start.

I noticed as I was messing with it, both before and after the carburetor replacement, that the throttle linkage doesn't appear to move the throttle plate inside the carb. (see pix below)

IMG_20240515_143258_0cr.jpg

IMG_20240515_143306_2cr.jpg
 
Throttle is fine they are suppose to be at full throttle when not running. That is how the governor works.

Here is a question since this is a primer system. If you direct prime the new carburetor will the engine start and run? If so then the primer is not working.

If so then it is a classic primer base failure due warpage.
 
Bertrrr said:
Verify it's getting fuel , it must have a spark if it ran for a few minutes, fuel lines tend to collapse and or dry rot if it's sat around for a few years
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Hi, thanks for your reply. In this case, fuel is gravity fed. If I don't pinch the hose when I disconnect it from the carburetor, fuel will spill out.
 
StarTech said:
Throttle is fine they are suppose to be at full throttle when not running. That is how the governor works.

Here is a question since this is a primer system. If you direct prime the new carburetor will the engine start and run? If so then the primer is not working.

If so then it is a classic primer base failure due warpage.
Click to expand...
I'll try the direct prime. The new carburetor came with a primer bulb, but I couldn't get it to fit, so I ended up reusing the old bulb.
 
The carb in the picture is Briggs part #799868. This carb uses air filter assembly #795259, which has the primer built into the filter base. Second, by adjusting the part where governor spring attaches to the throttle control (part with smaller hole) you can change throttle speed. Bending the part outward (grab the hole area with a needle nose pliers) will put more tension on the spring, allowing the throttle to open more. If you purchased a carb off the web there is a good chance that it will not work properly, or even mount properly.
 
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Okay, so I direct primed as mentioned in post #3 and the engine started and ran. It still will not start when I use the primer bulb. So that seems to be where the problem lies. I'll see what I can do to fix...
 
That's what I was getting at. These primer base warp from heat, age, and the screws being over tighten. I have repaired multiple of these. Take the air cleaner base and look the inside gasket impression. Most there is only a partial impression of the primer circuit. A lot folks want to double up the gasket. For me it is better to take two gaskets and make a wedge gasket (slice of pie look) applying more pressure in the area of non impression. Plain wood glue on the gasket works as just hold gaskets together until they bond to each other. Don't apply anything to the sides facing out or you will stop up the primer circuit.

BTW those screws are only tighten to 35-45 in lbs. Any tighter the plastic warps. While tightening look into the carburetor throat as you push the primer, when the area is sealed the main carburetor nozzle will have a fountain of gas to shoot up. Not blasting the opposite side but you see gas come up out of nozzle.
 
StarTech said:
BTW those screws are only tighten to 35-45 in lbs. Any tighter the plastic warps.
Click to expand...
I thought you crank them till you strip out the threads. Then hit it with your impact gun a few times. You know the old more is better approach? Joking.........

Really two fingers with your weak hand, using an OPEN grip is all you need. If you are a right hander, use your LEFT hand. Why? Most are not as strong in that hand limiting torque.
 
Believe or not I have seen the plastic around screws mush to paper thin by those techs trying to get the primer to work. And couple where screws were snapped off.
 
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