Craftsman 6.75 HP Flooding Problem

anseJune 8, 2008

I have two, nearly identical Craftsman mowers that I picked up for free because they were non running. I was working on them today and managed to get both running. However, I still have an issue with one of them.

After getting it running with some fresh gas, new oil and new filter, I pulled the plug and went down to the auto parts store to get a new one. When I got back, gas was coming out the spark plug hole and the bottom of the filter housing. I cleaned it up and put the new plug in. It ran, but the motor missed occasionally.

I mowed my lawn and let it sit for a while. When I tried to restart, gas was spewing out the exhaust manifold and the thing felt like it hydrolocked. Managed to get it loose by turning the mower on its side and letting the gas run out the exhaust. Started right up after that.

After sitting longer, gas was again coming out the air filter housing. Obviously I've got a carb flooding problem. How hard is it to pull one of these carbs and clean/rebuild? The model number for this Craftsman mower is 917.377593. Think it has the Tecumseh motor. Couldn't quite figure out how to drop the bowl on this one or remove the carb. Anyone have pictures or expertise with this type of mower?

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Take a pic before if you want to be sure how to re-assemble. They aren't difficult.Remove the bowl nut. Either a funky float or needle and seat. If the bowl is corroded at the seal area- replace that as well w/a new seal.

    Bookmark   June 8, 2008 at 3:00AM
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Thanks for the reply.

The mystery on this one is that it doesn't appear to have a bowl nut, unless I'm just not seeing it somehow. An older craftsman that I also have has an obvious bowl nut, but this one doesn't. The fuel line comes into what appears to be the bowl from the back. The carb looks like it's held on by two studs, which I am not quite sure how to get off (vice grips maybe?). A plastic air filter housing (square filter up front on the engine) with the primer bulb integrated into it mounts to the end of those studs with a couple of nuts. Air enters the intake from a rectangular hole on the left side of the filter housing, looking from the front. This is where the gas was coming from.

    Bookmark   June 8, 2008 at 9:18AM
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143.996704 is the engine # 640020B is the carb # Either # you can drop into the Sears model look up for a diagram. Buy a 730637a repair kit from any Tecumseh dealer to correct your problem. $20 and it slides right on after you slide the old one off. And likely a new air filter and oil as well.

Here is a link that might be useful: Sears

    Bookmark   June 8, 2008 at 1:15PM
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Thanks for your help. I'll look for the repair kit. Sounds like this is exactly what I need.

    Bookmark   June 8, 2008 at 10:01PM
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Also do change the oil. If it has a fuel problem you discribed,then there is also gas mixed with the oil!

    Bookmark   June 13, 2008 at 9:05AM
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I was having the same problem, so I changed the whole carburetor. Runs great now, except for it idles too high. I thought mowing a couple of strips would bring the rpms down, but it didn't. I turned it off and the mower backfired. Does anyone know how to adjust the idle on this carburetor? I cannot find a screw or anything that looks like you can use to adjust it.

    Bookmark   May 13, 2010 at 8:22AM
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