Briggs and Stratton 18 hp Twin II Flooding out

mrduck

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I have a MTD Yard Machine with a Briggs and Stratton 18 hp Twin oppose cylinder Model 42A707.

I have rebuilt carberator with new jets, needle valve, and cleaned. The problem is that it floods out as soon as I try to turn it over. Gas shoots out over the top of the top of carberator and dumping a lot of fuel down the intake.

I can start it cold with the throttle wide open but as soon as I try to back it down it quits, floods out.

I have called a lawn mower/small engine expert in the area and he doesn't have a clue. Does anyone know something I can try. It's got to be something simple I would think and I'm just not getting it. :confused2:
Thanks for any help, The Duckster
 

chance123

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It's kind of hard to diagnosis with the info you provided. 1rst I would check your crankcase oil and see if it is overfilled. (maybe even fuel in the oil) If fuel gushes out of the carb, it "could" mean a stuck intake valve. If an intake valve is stuck, the compression has nowhere to go except out the carb throat forcing out any fuel that the other cyl might have sucked in.
 

mrduck

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Thank you for your response. First of all there is no fuel in the oil, changed it. Also it is not overfilled, I checked. I have a compression tester and it's not that, it maintained the proper level. I appreciated your input, I need another head in this for input. The guy I talked to locally said it's got to be something simple but he can't check it for two weeks. I have a 1/2 acre I need to mow... :smile:
Thanks again, Duckster
 

Rivets

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I know that this may sound stupid, but I would to raise the float level. Have the float pointing up and bend the tang so that you will reduce the fuel level in the float bowl when the carb is reinstalled.
 

ILENGINE

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You didn't happen to get the air cleaner mounting gasket on wrong. If turned incorrectly it will block the carb bowl vent causing flooding like you describe.

Take the air filter off and look for a small hole around the edge of the carb intake and see if you can see through the gasket into the carb. The hole is about 3/16 in in diameter.
 

mrduck

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I know that this may sound stupid, but I would to raise the float level. Have the float pointing up and bend the tang so that you will reduce the fuel level in the float bowl when the carb is reinstalled.

Thank you for the thought but it's a plastic non adjustable float.
 

Rivets

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IL makes a good point about the vent and gasket. I would also check the gasket between the carb halves.
 

mrduck

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You didn't happen to get the air cleaner mounting gasket on wrong. If turned incorrectly it will block the carb bowl vent causing flooding like you describe.

Take the air filter off and look for a small hole around the edge of the carb intake and see if you can see through the gasket into the carb. The hole is about 3/16 in in diameter.

The model number is 42A707, it's not the model you're thinking it is. It can run without the air cleaner on it. Maybe if you can find something on this model? It's approx. a 2002 model MD tractor that I bought used. Thanks so much for your input or anything you can find out.
 

ILENGINE

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From the parts breakdown for that engine, which is the engine I was thinking about, it shows that it takes the oblong air filter. The gasket that I am refering to is the gasket between the carb and the air cleaner mount. If you get the gasket upside down or turned incorrectly, the engine will flood
 

mrduck

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From the parts breakdown for that engine, which is the engine I was thinking about, it shows that it takes the oblong air filter. The gasket that I am refering to is the gasket between the carb and the air cleaner mount. If you get the gasket upside down or turned incorrectly, the engine will flood

So are you telling me that this cannot run without the air cleaner? I have never seen any gas engine that can't run without the air cleaner, this would be the first and I'm 66. I really appreciate your input. Let me know, thanks.
 
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