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Discussion Starter · #1 ·
Hi All,

I need some help diagnosing an issue. This is on an LX255 JD Tractor. Here is he tractor details if it helps:

Tractor Data

The motor is a 15HP Kohler 426cc 1-cyl gasoline.

We had an unfortunate fire under the engine. I think it was just caused by a build up of leaves and other debris and was possibly ignited by the engine heat and/or exhaust. In any event, my wife was operating the mower at the time. She shut it off (and did not stall if that matters at all) and got away. The fire burned for about 60 seconds before I was able to get to it with an extinguisher and put out the flame.

I’m trying to assess whether it is worth trying to salvage the mower. It has run great. My Father owned it first and gave it to me. It is about 20 years old and has been perfectly reliable, so I am willing to put in a bit of work if it’s salvageable. Here is what I’ve done so far.

  • I checked the oil and it looks fine. It did not burn off.
  • The motor turns when I turn the key, but it does not fire or even try to start.
  • I checked the spark with a plug tester and I am getting continuous spark when cranking.
  • I changed the fuel filter
  • I’m taken off the fuel lines at several places up to the carburetor and fuel flows from each when cranking. It’s a slow trickle but it’s feeding fuel.
Before I start taking apart the carb, I’d like to understand what the above is telling me. There is a significant amount of fire damage to the wires on the right side (looking at it from behind) of the engine. If the engine wasn’t cranking and I wasn’t seeing a spark, I would have suspected that the safety wiring from the seat and/or from the foot brake was faulty and keeping it from starting, but as I stated this is not the case. So my first question:

Does the cranking and spark indicate that this non-starting issue is not related to the safety wiring form the seat and foot brake (or maybe it’s a clutch, I always called it a foot brake, but I mean the pedal you need to depress to start the mower)?

I’ll start there and if confirmed I will replace all of the fuel lines and dig into the carb. Is there anything else that I can do before disassembling and cleaning the carb to test other components. I’m not afraid of carb cleaning, I do it all the time, but I’d rather eliminate all other possibilities in front of the carb if possible. Given the fire, what other plastic or rubber components should I be looking at as a possible culprit?

If I can salvage this motor, I will post a different thread troubleshooting why the fire started in the first place....

Thanks in advance,
Rob
 

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Posting a few pictures might help.
 
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Discussion Starter · #4 ·
Also, the fuel shut-off solenoid is clicking and getting +12V when the key is turned. So spark is present, I'm seeing fuel coming through the fuel line, solenoid is clicking and reading +12V. I think that tells me that the engine should start, so I think cleaning the carb is my next step.
Thanks,
Rob
 

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Have you tried putting a teaspoon of gas in the carb throat and cranking it? Once you get the engine to run, make sure to check the lower crank seal for leakage.
Does this model use a mechanical fuel pump located below the carb and not too far from the muffler? Double check it for leakage!
Sorry you have to go through this, but happy you both are safe. I think you can fix that tractor and should give it a try.

tommyhawk
 

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That engine is eerily similar to the Kohler I had in an old Craftsman tractor. Alas, after 22 yrs I sold it last summer, so I can't go out to the barn to look at it for reference.

Have you pulled the sparkplug after cranking it for a bit, to see if the plug is wet? Wet means fuel is getting to the cylinder but not igniting. Dry means fuel isn't getting to the cylinder, and looking at the carb would be in order, since you believe the fuel cut-off is getting voltage. But keep in mind the solenoid might be getting voltage and clicking, but might not be opening the shut-off port.

Tommyhawk, the fuel pump is in the first picture, between the oil dipstick and the starter.
 
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Discussion Starter · #7 ·
Have you tried putting a teaspoon of gas in the carb throat and cranking it? Once you get the engine to run, make sure to check the lower crank seal for leakage.
Does this model use a mechanical fuel pump located below the carb and not too far from the muffler? Double check it for leakage!
Sorry you have to go through this, but happy you both are safe. I think you can fix that tractor and should give it a try.

tommyhawk
I haven't tried spooning some gas into the carb yet. I'll do that tomorrow. Thanks for the tips on checking the seal and fuel pump for leakage after it starts. Will do.

Rob
 

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Discussion Starter · #8 ·
That engine is eerily similar to the Kohler I had in an old Craftsman tractor. Alas, after 22 yrs I sold it last summer, so I can't go out to the barn to look at it for reference.

Have you pulled the sparkplug after cranking it for a bit, to see if the plug is wet? Wet means fuel is getting to the cylinder but not igniting. Dry means fuel isn't getting to the cylinder, and looking at the carb would be in order, since you believe the fuel cut-off is getting voltage. But keep in mind the solenoid might be getting voltage and clicking, but might not be opening the shut-off port.

Tommyhawk, the fuel pump is in the first picture, between the oil dipstick and the starter.
Good point about the solenoid, it could still be faulty. I'll do that with the plug as well. I always have a hard time determining if the plugs are wet or not. I will give it a try.
Thanks,
Rob
 

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Discussion Starter · #9 ·
Have you tried putting a teaspoon of gas in the carb throat and cranking it? Once you get the engine to run, make sure to check the lower crank seal for leakage.
Does this model use a mechanical fuel pump located below the carb and not too far from the muffler? Double check it for leakage!
Sorry you have to go through this, but happy you both are safe. I think you can fix that tractor and should give it a try.

tommyhawk
Also, thanks for the comment about us both being safe. It was a bit scary for sure.
-Rob
 

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Pull the plugs and dry them first. Then crank and re-pull 'em. Might be able to smell the gas too.
 
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Yep, first picture shows it all! My brain was thinking Kawasaki (leaking f/p hazard), but right there it says Kohler! Whole different animal. My advise on a dribble of gas would still be good. If it starts and runs for just a few seconds, the fuel supply would be the main thing to investigate.
Hang in there!

tommyhawk
 

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Discussion Starter · #13 ·
Hi All,

I got the LX255 started today.

First, it dawned on me that wasn't interpreting the spark plug tester lighting up correctly. That told me the coil was firing but not necessarily the spark plug attached to it. So I pulled the plug which was in pretty rough shape with carbon. So I swapped in a new plug. That didn't do it, and I was sure it was going to.

So I followed the sage advice of this forum and poured a bit of gas down the air intake. It took a few tries but eventually it turned over. It coughed and surged for several minutes, but eventually it smoothed out. I was expecting it to stall after a few minutes, but it ran for over 10 minutes. So I'm hopeful that maybe just getting it started cleared out a blockage in the carb. I shut it down, but had a very hard time starting it. Finally I had to pour a bit more gas down the intake and it fired up again. This time it didn't sputter or surge and I let it run for about 10 minutes again. The fuel filter filled with gas and it looks like it is pulling gas from the tank. I'm not sure how long this engine would run on a few ounces of gas. The last time I shut it down (or second to last time), I restarted it and it fired right up.

I was very excited until I pressed the gas pedal and nothing happened. My main drive belt was burned through and just hanging up there. No big deal but it kept me from doing a victory lap.

None of my safety features are working (seat or neutral foot pedal) so I have some work to do to get those safe again. Although it will not start with the deck switch in the running position, which is good. I'm also considering taking the time to give the carb a good cleaning while I'm greasy. That depends on how well it starts for the rest of this exercise. I'll replace any burned wiring while I'm at it.

Tomorrow I will order the belt and give the engine a good cleaning. I may be looking for some help with running the new belt.

Thanks for all of your help! Very Appreciated.
Rob
 

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I have the same model and changed the drive belt and one of the idler pulleys a while ago. I took this picture of the belt routing around the idler pulleys (broken idler on the left) before I started the job. Maybe it will help you out.
738576
 

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Discussion Starter · #15 ·
I have the same model and changed the drive belt and one of the idler pulleys a while ago. I took this picture of the belt routing around the idler pulleys (broken idler on the left) before I started the job. Maybe it will help you out. View attachment 738576
Nice! Thanks. Did you loosen those bolts on the idlers to drop them down a bit to get the belt around them? I noticed taking the belt off that I couldn’t just pull it out.
 

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When you replace the wiring, flex all of the wires down their length to see if the insulation is brittle and cracks. If it does, replace it, it will save you time in the long run chasing down shorts. Also pull all of your grounds and clean the connections with a wire brush, then re- torque, that will also save some running in circles knowing they have good contact.
 

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If it was my lawn tractor, I would pull the carburetor and check the plastic float for heat damage, and other heat related issues. The fuel pump diaphragm is probably damage also from the fire. Just do it right and replace the fuel lines, and any damage wires that have shown the fire damage. (One wire at a time) There probably no internal engine components damage, due to the fact it is a air cooled engine and it can take a lot of heat other than the seal at the lower crankshaft.
 

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Discussion Starter · #18 ·
When you replace the wiring, flex all of the wires down their length to see if the insulation is brittle and cracks. If it does, replace it, it will save you time in the long run chasing down shorts. Also pull all of your grounds and clean the connections with a wire brush, then re- torque, that will also save some running in circles knowing they have good contact.
Good advice which i will follow.
Thanks,
Rob
 

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Discussion Starter · #19 ·
If it was my lawn tractor, I would pull the carburetor and check the plastic float for heat damage, and other heat related issues. The fuel pump diaphragm is probably damage also from the fire. Just do it right and replace the fuel lines, and any damage wires that have shown the fire damage. (One wire at a time) There probably no internal engine components damage, due to the fact it is a air cooled engine and it can take a lot of heat other than the seal at the lower crankshaft.
Yes, I will tear down the carb. I'm having trouble keeping it running longer than 15 minutes or so after pouring some gas into the air intake, so I'm wondering now if I am actually getting gas from the tank. How long do you figure the engine would run from a few ounces down the intake?
Thanks for your comment.
Rob
 

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Nice! Thanks. Did you loosen those bolts on the idlers to drop them down a bit to get the belt around them? I noticed taking the belt off that I couldn’t just pull it out.
I think I must have lowered the pulleys to get the belt around them. I do remember unhooking the big tensioning spring and then having some trouble getting it hooked back up once the new belt was in place.

Yes, I will tear down the carb. I'm having trouble keeping it running longer than 15 minutes or so after pouring some gas into the air intake, so I'm wondering now if I am actually getting gas from the tank. How long do you figure the engine would run from a few ounces down the intake?
Thanks for your comment.
Rob
At idle, I'd expect the engine might run for a minute or 2. 15 seems a bit long, but maybe? If you could put a load on the engine, I think it would die out pretty quick.
 
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