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I have a Craftsman riding mower with Honda16.5hp engine(GXV530). The Mower started spitting and sputtering, so I changed plugs, air filter, checked valves, cleaned carb. Put everything back together. Left air filter out to start, and everything seemed fine. Got ready to mow, put (new)air filter in and mower started doing the same thing again. So today I started cutting grass and it just spit and sputtered. I pulled the (new) air filter and it ran like new. So confused. I had some experienced mower repair people talking me through this, but I'm stuck. I can cut with filter out, but I know that is not advisable. Wasn't dusty today. Would appreciate any input.

Take a close look for any wire or connector that might be in contact with the air cleaner/housing with it in place.

Running rich would cause it, choke working properly?

Does the crankcase breather go into the aircleaner base? Might try pulling the hose off that and running the air cleaner in place.

tom3 said:

Take a close look for any wire or connector that might be in contact with the air cleaner/housing with it in place.

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No wire - it sits in contained compartment with hinged lid and (2) thumb screws to hold it down

Mikel1 said:

Running rich would cause it, choke working properly?

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It only does this with air filter in. If I take it out it runs great. Choke seems to be working fine.

tom3 said:

Does the crankcase breather go into the aircleaner base? Might try pulling the hose off that and running the air cleaner in place.

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Yes, it does. I pulled it off at the air cleaner and it still spits and sputters. Blows a little black smoke when it sputters.

I have run a cross a motor that did as you described and it ended up being the valve lash was so far out that the valves were not opening enough to breath. Not saying this is your problem but something to look at.

MowLife said:

I have run a cross a motor that did as you described and it ended up being the valve lash was so far out that the valves were not opening enough to breath. Not saying this is your problem but something to look at.

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But with the filter out it runs like new. Could that still be the problem?

rickbrft said:

It only does this with air filter in. If I take it out it runs great. Choke seems to be working fine.

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I understand, I'm saying it's running too rich and that is why it runs good without the air filter on. With the restriction of the air filter on, it causes it too run even richer.

The main jet has fallen out or when cleaned has been enlarged
The float is not cutting off the fuel supply at the right height so the fuel is higher in the bowl

Both of these will cause the engine to miss & blow smoke filter on yet run fine filter off.

Excess blow by can foul the plug causing a miss fire filter on as well but you are getting into lottery winning odd on that one.

Ok, That makes sense. How do I correct that?

Cheapest thing is a new main jet.
Check the fuel height by jambing some fuel line in the bowl drain bolt hole then run it up the side of the carb.
The fuel height should be just below the gasket after a minute of engine cranking if it has a pump or a couple of minutes for a gravity tank.

NOTE :- the fuel solanoid will not affect the fuel height in the bowl unless you are silly enough to believe all of the shaved monkeys on face book and boob tube.

bertsmobile1 said:

Cheapest thing is a new main jet.
Check the fuel height by jambing some fuel line in the bowl drain bolt hole then run it up the side of the carb.
The fuel height should be just below the gasket after a minute of engine cranking if it has a pump or a couple of minutes for a gravity tank.

NOTE :- the fuel solanoid will not affect the fuel height in the bowl unless you are silly enough to believe all of the shaved monkeys on face book and boob tube.

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Thanks, I will look into that and let you know what I find.

Blows a little black smoke when it sputters.

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Black smoke = unburned fuel. Too rich.

Clean, rebuild or replace the carburetor.