Lx172 Runs Well for 29 minutes then stop!

   #1  

GBM

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Lx172
Hi,

My 1993 John Deere LX172 ran great and then all of a sudden stopped after about 20 minutes and wouldn’t run until it cooled off. I’ve cleaned the fuel tank, replaced everything from the tube in the gas tank to the carburetor including tube in tank, tubing, valve, filter, pump, and carburetor. Also filter and changed the oil. Next I replaced the coil and the firing order chip. After all this still runs for about 29 minutes and then stops. One thing that happens as it starts to stop is I get gas from the carburetor thru the short tube releasing gas onto the frame of the tractor.
I’ve had a repair shop look at it and they tightened the carburetor which I had replaced and replaced the fuel filter just because they felt that was the fix.
No fix as it still does the same thing, and ideas of what I can do next?
Gary Morgan
 
   #2  

BravoXray

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Does it stop like you turned the switch off, or does it start slobbering or missing and die.
Does it have spark after it dies?
 
   #3  

Roadworthy

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Disconnect the fuel line just before the carburetor. Make sure you have good fuel flow there. It's possible you've shaken something loose in the tank which is partially blocking flow but allowing enough flow to refill your lines and refill the carburetor as the tractor sits. It's also possible your new fuel filter is defective. As a test you could try running with no fuel filter in place. Is the float in your carburetor sticking, preventing or slowing fuel flow into the carburetor. Is the needle valve sliding freely or sticking in any way? By all means, exhaust the dumb stuff before getting into the expensive things.
 
  
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#4  
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G

GBM

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Does it stop like you turned the switch off, or does it start slobbering or missing and die.
Does it have spark after it dies?
It starts slobbering and dies, no backfiring at all.
 
  
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#5  
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G

GBM

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It starts slobbering and dies, no backfiring at all.
 
  
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#6  
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G

GBM

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Disconnect the fuel line just before the carburetor. Make sure you have good fuel flow there. It's possible you've shaken something loose in the tank which is partially blocking flow but allowing enough flow to refill your lines and refill the carburetor as the tractor sits. It's also possible your new fuel filter is defective. As a test you could try running with no fuel filter in place. Is the float in your carburetor sticking, preventing or slowing fuel flow into the carburetor. Is the needle valve sliding freely or sticking in any way? By all means, exhaust the dumb stuff before getting into the expensive things.
 
  
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#7  
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G

GBM

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I’ve tried all of this with a new carburetor, as that what I though was the issue, fuel flow but I’m getting good flow to the carburetor and in fact when this happens I get fuel from the carburetor drain line flowing out of the carburetor onto the tractor frame which is dangerous on a hot engine.
 
   #8  

tomplum

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So your carburetor starts to overflow and it dies? Sounds like you've found your answer. I'm guessing that carb didn't come out of a Kawasaki box.
 
  
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#9  
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GBM

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Actually your correct but the original factory carburetor that I replaced did the same thing. To me it seems like the carb is working but it stops getting pulled into the manifold or just maybe my spare plug wire i bad when it gets hot??
 
   #10  

tomplum

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The problem with these knock off carbs is that they turn into tail chasers. The carb won't overflow if it is working properly. Maybe you can lower the float level in the carb and keep the vent in a position to where it doesn't turn into a siphon. Is there another vent in the venturi that is blocked?
 
   #11  

michiglenn

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Hi,

My 1993 John Deere LX172 ran great and then all of a sudden stopped after about 20 minutes and wouldn’t run until it cooled off. I’ve cleaned the fuel tank, replaced everything from the tube in the gas tank to the carburetor including tube in tank, tubing, valve, filter, pump, and carburetor. Also filter and changed the oil. Next I replaced the coil and the firing order chip. After all this still runs for about 29 minutes and then stops. One thing that happens as it starts to stop is I get gas from the carburetor thru the short tube releasing gas onto the frame of the tractor.
I’ve had a repair shop look at it and they tightened the carburetor which I had replaced and replaced the fuel filter just because they felt that was the fix.
No fix as it still does the same thing, and ideas of what I can do next?
Gary Morgan
I had the same frustrating problem for a whole season, running well for about 10-15 minutes, then sputtering and dying. After letting it set (or checking for fuel in the tank) it would run again for 10 minutes, and repeat. Watching carefully one day, I saw that the tank was actually collapsing from vacuum. Finally it made sense, I bought a new cap with a clean vent hole and have had no issues whatsoever for about 5 years. The symptoms you have are identical to mine. It's worth a look...
 
  
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#12  
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GBM

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I just ordered a new carburetor and gas cap. I hope one of these fix this issue. I’m also going to replace my spare plug wire just to complete my rebuild.
I checked buying a new tractor but this one is a great asset and does everything I need with still solid parts replacement.
 
   #13  

therrien

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Same machine with a kawasaki engine, had the same problem and I play with small engines as a hobby. This drove me crazy. REPLACE SPARK PLUG
Because spark can be seen you look no further but as it gets hotter the plug fails.
Be sure to replace plug. I only did this after many other trouble shooting steps and I stock 100+ plugs. I called myself an idiot for hours after.
 
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#14  
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GBM

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I did this already because I thought the new plug I put in I had the gap wrong. Still going to replace spark plug wire.
 
   #15  

CalG

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It's hard when you are working on fuel issues, but suspect ignition. How will you know what fixes the problem?

A timing light is a great way to evaluate ignition problems. I have TWO older Sears timing lights. I wouldn't be caught without one!

Fuel issues can be scoped out with a spray bottle of gasoline. Direct injection into the carb throat! Unless flooding is obvious. It takes a LOT of gas to not get pops and bangs with good ignition and good plugs. Wet plugs can be dried by pulling them and cranking the engine with the plugs happily sparking while laying on the engine or other grounded surface.

Coils that get hot will quite sparking if defective. I assume there is no condenser. 20 minutes is a long time....
 
  
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#17  
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G

GBM

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Yes but I have to use the chock to keep it running but still it will only run for a very short time and then will not start at all.
 

Richard001

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Yes but I have to use the chock to keep it running but still it will only run for a very short time and then will not start at all.
I don't think that you answered Bravo's question.
 
  
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#19  
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GBM

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I purchased a new John Deere carburetor and as soon as it’s delivered I’ll install and see if that fixes the issue.
Thanks to all who helped by providing their thoughts and experiences. I’ll let you know the results.
Gary
 

Gator6x4

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This may help or provide information.

 

Richard001

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Nonsense.
 
 
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