# Honda riding lawnmower engine floods



## birdman350 (May 27, 2010)

I have a craftsman riding lawnmower with a 16HP Honda engine. The engine has no model number that I can find but it is very similar to the GXV530 as it looks identical and I have come across this model cross referenced on some of the parts that I have bought.

Last season the engine started flooding (blowing black smoke) and was running very poorly so I changed the air filter and pre-cleaner. I saw no improvements so I removed the carburetor disassembled, soaked and cleaned it. The problem was still there so I bought a new carburetor, fuel filter and spark plugs from Sears and installed these parts but it still ran rich. When I removed the air filter I noticed that there was raw fuel sitting in the plastic fresh air intake under the air filter. At one point I came to the conclusion that it was getting too much fuel pressure and the diaphragm fuel pump was somehow outputting too much pressure so on a long shot I replaced the fuel pump but still the problem exists. I can take the hose that is connected to the fuel pump from the crankcase that operates the diaphragm so that the fuel pump no longer pumps and the engine will run perfect with no black smoke until the carburetor bowl runs out of fuel and starts to die. I have managed to use the lawnmower the last two times by partially pinching the fuel line off with a cotter pin between the gas tank and fuel pump but I have to adjust my little rig job a few times as it will start starving or running rich.

I'm not sure what I'm missing here but it seems to me that the fuel pump pressure is overcoming the float and needle and causing the flooding. I'm about ready to buy another carburetor, a new engine or a new lawnmower since I am getting very frustrated with this thing.

P.S. Last season I ran it with the fuel pump pick-up tube in a jar of fresh gas just to eliminate bad gas and it still flooded out.


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## birdman350 (May 27, 2010)

I think I may have finally fixed it. There is a vacuum tube that is connected on top of the carburetor that vents to atmosphere. I took it off this morning and tried to blow through it. It seemed a little restricted so I blew compressed air through it and now it seems to run normal.

I think just typing the above post helped me re-think the problem. Thanks for listening and maybe this will help someone else.


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## boot (May 21, 2019)

Honda glues one gasket to the manifold and glues a gasket and spacer to the carb for assembly line ease. Did you pull the gasket and spacer off the carb? The air vent passageways from the top to bottom were plug with insect nest? and absolutely caused the engine to flood on the one I worked on.


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## finaprint (Jan 29, 2006)

It's likely an air bleed which ADDS air when open, a true vent if clogged cuts fuel flow off by making a vacuum in the fuel bowl. Clogged to run richer screams air bleed instead, the extra air cuts the amount of vacuum applied to the fuel and then the carb leans out. Two different actions there.


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