Craftsman small push mower just won't stay started


Old 04-15-12, 10:03 AM
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Join Date: Jun 2004
Location: Butler
Posts: 65
Craftsman small push mower just won't stay started

Hi all,

I have a 4.5 horsepower Craftsman lawn mower. It's been a champ for a number of years, but this year it won't stay started.

The spark plug is getting on in years, but it looks good, and I have no problem starting it. The air filter is dirty, but again, not sure that's really the problem.

I prime it, and it starts and runs for a few seconds, then dies. I find that if I keep priming it, it will stay running for as long as I prime it. There is a small lever type mechanism on the carburetor that opens and closes, and that seems to be what's causing it to die. I can grab that little lever, hold it about halfway, and it keeps the mower from dying.

Talked to my local shop, and they recommended carb cleaner. So I bought some gum-out, and some premium gasoline, and threw it all in there. It helped, definitely, but it still dies. (the gas is from last year, but I've done that every year)

So, not sure what else to look for. This mower has no fuel filter, so I can't replace that. I took a video of me trying to run the mower (sorry it's shaky, but it's the best I could do by myself).

Lawnmower won't stay started - YouTube

Any ideas for what to do to fix this???

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Old 04-15-12, 10:07 AM
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Join Date: Jun 2004
Location: Butler
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PS - that lever is pulsing back and forth, speeding and slowing the engine. It wasn't doing that before the carb cleaner. But I imagine it is supposed to stay in one place... Also, that is my foot priming the engine at the end there...

Thanks for any advice.
Old 04-15-12, 10:43 AM
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It comes down to cleaning the carb and how you want to go about it. You can take it off, dismantle it, soak it in carb cleaner, then blow it out with compressed air and stick it back together. That will probably do it.

Or I come back to trying Sea Foam first. It's a cleaner you put in the tank. Get it at an auto parts store. Put it in start the engine and let run til it dies. Let it sit half an hour, Then start it up and see where you are. It'll continue to clean until the varnish is gone. The more varnish the longer it takes. The performance will improve until it's cleaned up.

Either way it sounds like a cleaning job is in order.
Old 04-15-12, 10:58 AM
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Pinch the fuel line shut with a pair of vise grips, take the bolt out of the bottom of the carb bowl, pull the bowl off. With a can of spray carburetor cleaner from the local auto parts place, clean the bowl and the bolt that holds it on. Use a wire from the middle of a bread bag twist tie to clean the tiny holes in the bolt that holds the bowl on, and put it back together. Should take 10 minutes and only 1 bolt removal.
Old 08-19-12, 01:15 PM
Join Date: Aug 2012
Posts: 1
Mower dies after running a few seconds

I have a Craftsman 5.5hp and it ran great until a week ago. Starts and just dies. I could keep it running by pushing the primer bulb so I knew it was the carb. I cleaned, checked nozel holes, replaced diaphram caskets, all to no avail. The carb is basically one unit so there isn't much else to do. On the bottom of the small intake is a wrap-around grey filter that looks a bit like duck tape. The longer tank feed has a filter on it so I decided to just remove the grey small mesh filter, it twist off and the fact that this is the way it is attached shows that over time it can lossen up and actually plug the feed. Anyways, I took it off, reassembled everything and the mower runs like a champ.
Old 08-19-12, 07:00 PM
Join Date: Oct 2011
Location: USA
Posts: 433
Take the carburetor off and check main jet that holds float bowl on like cheese said but also inspect to see if the o-ring in the bottom of the main jet tube is detereated, if it is remove main tube and replace both o-rings, one in top and one in the bottom sealing the bowl nut. Make sure to clean really good, top o-ring is very hard to see and over looked A LOT!! These carbs can be a pain but once you get it right it will run like a champ,,good luck.

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