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Discussion Starter · #1 ·
I have a ten year old craftsman lt1000 that I bought new. It has had pretty regular maintenance but had been giving me trouble since the end of last year in terms of reliability in mowing. It would run for about 20-30 minutes and the sputter, rev and die. So before storing it for winter I drained the gas and took out the battery. Before this season, I put new gas in the tank with some stabilizer and bought a new battery. All was good the first time I mowed the lawn. The second time, it ran for a half hour and would sputter, rev and die. If I let it sit, I could restart it but the whole process would start over again. I took it to the local small engine repair shop and $175 later he rebuilt the carb, replaced the oil and filter, changed the spark plug, put on new blades, leveled the deck and a couple other minor things. I got it back and it did it again the first mow. So I did some research, talked to some friends and family and troubleshot. All signs pointed to a failing ignition coil so I ordered a new one and replaced it. Same thing happened. Replaced all fuel lines and filter, adjusted the valves to .004, sea foamed the engine.........it still happens. I get about halfway done with my back yard and it sputters, revs and stalls - acts as if it is flooded. If I let it sit for 10 minutes or so it starts right back up and I can get another 10 or 15 minutes before it happens again. I am at a loss as to what the problem could be. It seems to be vapor lock so I wrapped the exhaust pipes in insulation to see if the heat was causing the gas to evaporate too quickly. It is a gravity fed system so no fuel pump. The gas cap vent is clear but I have ordered a new one just to see if that's the culprit. I also don't want to continue sinking money into it, but in poker terms I feel as though I am pot committed at this point.

So I guess I am just asking if any of you have experience with this stuff and what else could I look for? One of the things I haven't checked yet is the safety switches - could this be an issue with the way it is acting? And I have heard that the 87 octane gas can be the culprit.....is this possible even though I have used it for ten years???? The engine fins have been cleaned.

In short, I am at a loss. Is there anything any of you good people could recommend to me to troubleshoot at this time?

Thanks in advance,
Shawn
 

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Hello and welcome to MLF shawn. It sure sounds like a faulty gas cap vent to me. Try running with the cap loose and see if the problem persists until you get a new cap.
 

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:ditto: That would be an easy way to check it out. Also, make sure the float in the carb isn't sticking, even though it's been rebuilt.
 

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Discussion Starter · #5 ·
Thanks guys, I ordered a new gas cap so will see if that's the problem. Loosening the gas cap did nothing to cure it though. I will check the float again. I sprayed carb cleaner in it again just to suu if that would do the trick and it did nothing. The fuel filter is brand new OEM. Thanks again for the suggestions.
 

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Not too sure I'd have ordered a new fuel cap if loosening it doesn't help.. If it ain't broke don't fix it.
 

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-When it coughs, sputters and dies, do you still have spark at the plug?

-Check fuel flow when it sputters and dies, maybe a sheet of varnish floating in the tank. When it covers the fuel outlet of the tank it chokes off the fuel lines. I had his happen to a RER rider that was driving me up the wall. I checked the fuel line and there was barely a trickle of fuel. I looked into the tank with a flash light and I saw the sheet of varnish floating around. I removed the tank and rinsed if out thoroughly and it cured the problem.

-Also, it may just be the tank isn't quite high enough in the chassis for a good gravity feed. I worked on a Craftsman w/ Kohler Command 15.5 HP and when the tank ran low it would starve for fuel. It never, ever ran out of gas completely.

Just my .02, good luck!
 

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I'm not sure what engine you have, but a lot of riding mowers have an anti after fire (backfire) solenoid on the bottom of the carb bowl. If the coil is overheating and shorting out, the needle valve will be released and stop gas flow to the carb. The solenoid is energized when the ignition switch is on and pulls the needle valve down allowing fuel to flow. You could pull the solenoid off immediately after the engine dies and check operation of the solenoid to see if that is the problem???

:2cents:
 

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Is there an internal fuel screen/filter inside the tank at the fuel outlet? I've ssen them get clogged up and cause issues a s well. Had a rototiller with this problem. Look down in there with a good flashlight.
 

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What about decaying or cracked fuel lines? Fuel filter? They may or may not leak gas, but allowing a little air or something interrupt the flow.
 

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Discussion Starter · #12 · (Edited)
Thanks again for all the feedback. I wouldn't think it would be anything fuel related - the location of the tank has never given me a problem before in terms of flow. The engine still has spark when it stalls. I will check for the tank filter and see about debris but when I take the fuel line off it flows freely so can't imagine there is an obstruction. I am leaning towards the safety switch too and come to think of it there has been a problem intermittently that my blades don't stop spinning when I disengage. It lasts for a few seconds and usually will stop if a gently hop up on the seat. Only happens once in awhile though and doesn't correspond to the initial problem. Think these could be related? How would I jump the switch?

I will try to check the solenoid operation this weekend. I guess my question would be why now? The engine heat should he the same as always and considering it is a new ignition coil, this should not be happening, correct? Want to cover all my bases though so will test it out.
 

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Discussion Starter · #14 ·
Got around to troubleshooting again today. Turns out the anti backfire solenoid went bad and was malfunctioning. So I removed the plunger portion of the solenoid, reinstalled it and let it run for 40 minutes. Purred like a kitten and didn't stall. I have ordered the replacement part and will I stall it next week. In the meantime I guess I will have to wear earplugs!

Thanks again all, this place has been very helpful and hopefully I can help someone the same way in the future.
 

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Got around to troubleshooting again today. Turns out the anti backfire solenoid went bad and was malfunctioning. So I removed the plunger portion of the solenoid, reinstalled it and let it run for 40 minutes. Purred like a kitten and didn't stall. I have ordered the replacement part and will I stall it next week. In the meantime I guess I will have to wear earplugs!

Thanks again all, this place has been very helpful and hopefully I can help someone the same way in the future.
Glad to hear you found your problem. :ThumbUp:
You can minimize the backfire by throttling down and let the engine idle for a minute before turning off the ignition.
 

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Discussion Starter · #17 ·
So the darndest thing happened today. Got a new solenoid today, installed it and the tractor would run for two minutes, Rev and stall again. Took out the new solenoid, swapped it out for the old one with the snipped off plunger and it ran fine. The gas from the card loomed orangish which I don't recall before. Could that be from the previous seafood treatment? Any advice again is appreciated. Is there a problem not having the senior function properly besides the backfire?
 

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I'm not a mower mechanic and I'm fighting my own mower demons at the moment but I see your post on it's 3rd day with no response so I'll try to answer your questions. First, I'm guessing you have some typos so let me clarify. Is "card loomed orange" supposed to be carb looked orange? And "seafood" = seafoam, "senior" = solenoid? If so, I'd say your gas color may be the result of a gas treatment, although I've been using Seafoam for years and never had it turn my gas orange. Is it possible the shop you took it to put a fuel additive in the gas? To my knowledge, the one and only purpose of the solenoid is to prevent the backfire and disabling it should have no effect on the motor other than it may backfire when shut off.
 

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Discussion Starter · #19 ·
Yes thanks for your post. Those were correct assumptions and apologies for the typos. My new android phone auto corrects and I can't stand it.

I actually think what happened was that I did not install an in line fuel shut off valve - I read you should do that in order to prevent fuel mixing with oil. So I will do that this weekend and see if it fixes the problem. I changed the oil and filter just to be safe. Hopefully that's all it was and this will solve it once and for all. If not I will use it until it dies and move on. I am finished trying to figure this thing out. It runs and mows and if it can me through the fall (leaf season) I will be happy and start saving for a new one this winter. Or it will fix it and I can continue to use it and save money for something else.
 
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