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Discussion Starter · #1 ·
Hello All, I sole owner of a 1998 JX75 John Deere walk behind mower. This mower has served me well for over 20 years. Now it has issues. It starts cold like normal and runs for about a minute. Then it shuts itself off. It’s impossible to start afterwards but it gives false hope to keep me pulling on that rope: it pathetically runs on without throttling up, and when it doesn’t do that, it backfires through the carb. I suspect dirty carb causing lean burn. I have cleaned it three times. Each time the mower starts and runs well until I am finished mowing and turn it off. Next time I go do use it, I repeat the process. Symptoms point to lean, but I am stumped. Help (please)!
 

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it could be the fuel line coming apart internally and blocking things up. I had the same issue with a RX75 Riding mower, clean the carb, ran great, fire it up a week later, it would run out of fuel in the bowl, take the carb off ,clean it, hmmm little black specks of stuff in it.. i took the fuel line off completely, and a big ball of detoriated gas line came out.

I would also check to see that the Primer/ Choke is working, whichever it has.
 

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Discussion Starter · #3 ·
I will check the fuel line, as once again, I had to clean the carb to cut my lawn. It does seem to behave as though an invisible hand is shutting off the gas flow.
 

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I will check the fuel line, as once again, I had to clean the carb to cut my lawn. It does seem to behave as though an invisible hand is shutting off the gas flow.
During dismantling some people have a habit of plugging fuel lines with a threaded bolt. When the bolt is pulled out it roughs up the inside of the line and eventually those little bits of rubber end up causing trouble.
Getting back to your JD, has it ever had a valve / top end job? In 20 years the clearances could have reduced to the stage of being non existent when hot.
 

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During dismantling some people have a habit of plugging fuel lines with a threaded bolt. When the bolt is pulled out it roughs up the inside of the line and eventually those little bits of rubber end up causing trouble.
Getting back to your JD, has it ever had a valve / top end job? In 20 years the clearances could have reduced to the stage of being non existent when hot.
Yeah, that could be the case.. JD used a Briggs flathead Quantum as well as a Kawasaki FJ180, OHV engine on these as well.
 

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Discussion Starter · #6 ·
Well, I think I found the problem: instead of cleaning this “new” plug, I was being lazy and grabbed another new one, and it fired right off! Ran like it was new! So I assumed the plug was good...and wore out my arm pulling the cord. Looks like I made this problem bigger than it was. Oh yes, fuel line is still good, and it is the Kawasaki OHV motor.
Thanks everyone!
 
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