Craftsman mower won't start. Cleaned carb. What else to check?

ilyaz

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Have this Craftsman mower that was running when someone gave it to me, but I can't get it to start. Watched a bunch of YT videos, cleaned the carb (or I think I did) but still nothing. When I pulled out the spark plug after trying to start, the business end of it was bone dry. So carb still clogged? Something else? TIA!

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Scrubcadet10

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Remove the carb, take off the bowl, the bowl bolt you remove is the main jet. there are 3 holes in, two going crossways at the base, and one in the top of it, be sure those are clear... spray it out and run a small wire or something in to clear out any crap.
also clean the emulsion tube, which is what the main jet screws into, you'll see the hole that goes up into the venturi of the carburetor.
also be sure that your float level is good, with the float on tip the carb where the float is facing up, and it should be level across the top of the float, and if it is slightly angled down that is fine too.
 

tom3

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Might take out the plug, spray in some starting fluid, replace plug and see if it starts and quits. If so probably a carb or fuel supply problem. That red round button on the air cleaner is a primer, push it several times before starting.
 

slomo

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Now THOSE are pictures. Thanks for the clarity. (y)

As Bertsmobile1 said, there's
clean then there's clean.

Remove the car-bu-trator. Remove the bowl gasket, plastic float and needle (needle and seat). Remove the main jet and emulsion tube above it. Pilot screw gets removed also. Place the carb body in the dish washer on pot scrubber cycle. Make sure the wife is at the nail salon when you do. Remove and blast with carb cleaner both directions in every hole you can possible find. Wear magnifying glasses if needed or safety glasses for sure. You will know if you get carb cleaner in your eyes. Blow out with an air compressor both ways. Might take another cleaning or three.

Scrubcadet10 above gave some great tips.

slomo
 

seattlepioneer

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I recently had the same engine that wouldn't start. Very likely the problem was that the engine wasn't getting fuel. So I tried cleaning the carb ---several times, then replacing the carb. Replacing the rubber fuel line ---washing out the fuel tank with gasoline to be sure there was no debris that could be fouling the carb.

Nothing helped.

Then I discovered the actual problem. When you mount the carb on the engine, you push the outlet of the carb onto a rubber o ring. The o ring is mounted on a plastic part that conducts the fuel air mixture into the engine, and that plastic part was broken.

This isn't quite obvious by just looking at it ---but I'd check it with some care since it can be the source of your problem.
 

ilyaz

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Then I discovered the actual problem. When you mount the carb on the engine, you push the outlet of the carb onto a rubber o ring. The o ring is mounted on a plastic part that conducts the fuel air mixture into the engine, and that plastic part was broken.

This isn't quite obvious by just looking at it ---but I'd check it with some care since it can be the source of your problem.
Was your plastic part cracked? Was it simply blocking the mixture flow or redirecting it somewhere? I am assuming you replaced the part? Do you happen to have a URL for a replacement? Or just the name? Thx
 

seattlepioneer

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<<
Then I discovered the actual problem. When you mount the carb on the engine, you push the outlet of the carb onto a rubber o ring. The o ring is mounted on a plastic part that conducts the fuel air mixture into the engine, and that plastic part was broken.

This isn't quite obvious by just looking at it ---but I'd check it with some care since it can be the source of your problem.
Was your plastic part cracked? Was it simply blocking the mixture flow or redirecting it somewhere? I am assuming you replaced the part? Do you happen to have a URL for a replacement? Or just the name? Thx >>

This plastic part, which the rubber o ring fits over, was cracked/broken all the way around so that it came away in two parts when I replaced it.

I had another decomissioned engine of the same type, so I simply took that part off the decommissioned engine,

I had spent a LOT of time looking for other reasons the engine wasn't getting fuel. Quite possibly this defect is rare, but after you've tried more common reasons for the engine not getting fuel, I'd look carefully at this part, since I guarantee you it's a possible cause for the engine not to run.

When you have the carb off the engine and you can see the rubber o ring, that's a good time to look carefully for a crack in that part. There was one other part that blocked your view of that part, but that could be removed fairly easily.

I was really quite proud of myself for finding this defect, which no one had suggested.

I'd be interested in finding out how common this problem is. How often is this a cause of an engine not running?

This is on the B&S carburetor part 799868.

The part that was broken was the intake manifold, part 794305

When you take the carburetor off the engine, you can see the rubber o ring that is on the end of the intake manifold.
 
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