gregww

Well-known Member
When my MIL passed about 10 years ago I inherited an STX38. I do not know the model or serial number. I can tell you it DOES NOT have a fuel solenoid on the carb. She had a lot of trouble with the tractor dyeing all the time. It would not restart until it sat for a couple hours. Turn over just fine, just would not fire. She had it at JD dealer several times, but of course they could not replicate the problem. I brought the tractor home figuring I could fiddle with it, give me something to do. Trouble is, I could never replicate the problem either. Ran fine for me for years, until one day it made a horrible noise and died. I thought it was dead for good this time. I went out and bought a new X370. I decided to tear into the 38. I knew nothing about small engines but I figured I could not hurt it any. Long story short, it swallowed one of those little brass screws from the butterfly in the carb. I replaced the screw, head gasket, and put it all back together. Fired right up and ran fine. I gave it to my son last year, knowing it would probably not last long. He is part of the use it-abuse it-throw it away and get a new one generation... Trouble is he usually gets a new one from me, whatever it is. This year he is having the same trouble as my MIL. Mower dies, will not restart, turns over fine. He says there is no fuel running down the fuel line to the carb. I have had the mower die on me if it was less that 1/3 full of gas and I was on a side hill with the carb on the uphill side. If I could get turned down hill quick enough, gas would flow, and it would keep running. My sons yard is completely flat. No hills at all. I am not sure where to start. When it happened earlier this year I went to his house and removed the carb bowl, kind-a cleaned out the bowl, put it back together, turned the fuel back on, and there was plenty of gas. It ran fine. Now apparently it is dyeing on a regular basis. Would the float stick in the up position, keeping the gas from flowing? Or maybe just the needle sticking occasionally? Kind of reminds me of vapor locking problems my dad had on his Pontiac back in the 60's. Is that possible? I'm not even sure what vapor locking is to be honest. Any help would be appreciated. Thanks Greg
 
I would check the fuel cap. If its not venting, that could cause this problem.

You also need to know if its losing spark or fuel when it dies. Harbor freight sells an in-line spark tester that is pretty reasonable.

If its the single cylinder Kawasaki, that little module on the side opposite the carb. can play tricks. Like no spark when hot.

But you need to know what you are losing, fuel or spark when it quits.

It could also be valves out of adjustment, as in the valves have no clearance when hot and a valve is not sealing.
 
Greg I hate STX38 mowers. I had 1. Worst
mower I ever had. Does it have any
compression when it does. Dads had a valve
seat lifting on it. When it got hot the
seat lifted out if the block, motor died.
When it cooled down the seat would drop
back in place and it would run again. Good
luck with your problem.
 
I have had 2 of the STX38s. One I bought cheap because of the carb butterfly screw was on top of the piston and several motor mount bolts were broken. Used and abused!! The first one Kids were ramming it in different gears until the broke the differential housing. Bought parts and fixed and gave it to my son who used it for years. Mine works great but I had problems with it stopping and wouldn't run until it cooled off. It was a Module on the side of the engine cooling shroud. Has worked great for probably 10 years now. I know the black decks were not as good as the yellow deck. I worked at a JD dealer for a number of years.
 
I have never been present when the tractor died. My son used the tractor all day yesterday moving rock, no issues. I told him the next time it dies to leave it sit and call me. I have a spark tester, so I can check that. If and when I find anything, I will let you know the results. Thanks Greg
 

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