I have a John Deere LT170 riding mower with a 17HP Kawasaki V-twin engine that up until this spring has been a good running a reliable mower. early this year after mowing for about an hour or so, It suddenly started losing power and wouldnt haul itself any further let alone mow, after cooling for a few hours it fired right back up on the first crank, finished the yard and drove back to the garage no problems. It didnt seem overly hot and i keep up with all maintenance on it religiously. Thw next two times mowing, it did the same thing. i checked all electrical connections and interlock switches, cleaned the air filter, changed the oil, took the bowl off the carb and drained and cleaned. ran great for a few times mowing but started acting up again even faster. this time i dropped the fuel tank and drained and let dry before replacing and refilling, changed the fuel filter again, and even changed the fuel pump (one of the vacuum impulse type) tore the carb completely apart and cleaned thoroughly. didnt seem to help this time, now, i can barely mow by choking the mower about 1/3rd of the way. a parts guy at the local JD service Dept suggested checking the fuel shutoff solenoid on the carb, will try that tonight, running out of ideas though, anyone have any ideas/suggestions or a similar problem?
JD LT170 have to choke to keep running
- Thread starter severnia
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I read your post and did not see any referance to changing the gas cap. Did you check the vent hole in it? A plugged vent hole will break the diaphram in the fuel pump. It is possible the second one (fuel pump) went bad. When bad they usually leak gas out the vent hole in the bottom of the pump. If it has a rubber drain tube the gas will exit through it. You should be able to smell gas.
The other thing that can cause your problem is rodent chewed wires. Check between the ign and starter for chewed wires, look real close around and under the battery and up to the starter. If you find one cut the wire and put in a splice. A crimp connector splice works well. I have the same engine and have had the same problem. Found a chewed wire that would lose contact internitantly.
The other thing that can cause your problem is rodent chewed wires. Check between the ign and starter for chewed wires, look real close around and under the battery and up to the starter. If you find one cut the wire and put in a splice. A crimp connector splice works well. I have the same engine and have had the same problem. Found a chewed wire that would lose contact internitantly.
@ fixemall
ok, i have the carb fully disassembled and soaking in carb cleaner for the evening, sadly this is about the best i can do as i dont have access to a parts washer of any sort, i did a thorough inspection of it and could not find any gunk and particles in any of the jets or vents, though initially there was some sediment in the bowl when this all began. 5 or 6 cans of carb cleaner later it has to be about as clean as it left the factory.
@rayikeo2
I havent changed the gas cap yet, but i have tried running without it for a bit to see if it could be a vapor lock in the tank.
I have looked over a good part of the wiring as I Initially suspected a faulty switch or connection at a safety interlock after reading some things online and cleaning the carb out the first time. I will go over the harness with a fine tooth comb tomorrow and double check everything as i did have to replace my fuel line last year thanks to rodents ...
On a side note, i have a suspect after this evening, after talking with the JD service tech today, i checked the electronic fuel cut off on the bottom of the carb and found with voltage applied it would not always pull in as it should, if helped, it would remain in, but would not pull in under its own power. i verified this with a fully charged Jump pack also. I bought some emery cloth and electrical connector cleaner spray and cleaned the ignition switch connector, the 3 pin connector going to the motor, and every other electrical connection i could find. they were a bit dirty and full of gunk, but after cleaning it still wouldnt pull in the fuel cut off solenoid. JD wants $62 for the silly thing....
Thanks for the help so far everyone
ok, i have the carb fully disassembled and soaking in carb cleaner for the evening, sadly this is about the best i can do as i dont have access to a parts washer of any sort, i did a thorough inspection of it and could not find any gunk and particles in any of the jets or vents, though initially there was some sediment in the bowl when this all began. 5 or 6 cans of carb cleaner later it has to be about as clean as it left the factory.
@rayikeo2
I havent changed the gas cap yet, but i have tried running without it for a bit to see if it could be a vapor lock in the tank.
I have looked over a good part of the wiring as I Initially suspected a faulty switch or connection at a safety interlock after reading some things online and cleaning the carb out the first time. I will go over the harness with a fine tooth comb tomorrow and double check everything as i did have to replace my fuel line last year thanks to rodents ...
On a side note, i have a suspect after this evening, after talking with the JD service tech today, i checked the electronic fuel cut off on the bottom of the carb and found with voltage applied it would not always pull in as it should, if helped, it would remain in, but would not pull in under its own power. i verified this with a fully charged Jump pack also. I bought some emery cloth and electrical connector cleaner spray and cleaned the ignition switch connector, the 3 pin connector going to the motor, and every other electrical connection i could find. they were a bit dirty and full of gunk, but after cleaning it still wouldnt pull in the fuel cut off solenoid. JD wants $62 for the silly thing....
Thanks for the help so far everyone
Checking your wording on the fuel shutoff cylinder. When power is put to the shutoff it opens by retracting the plunger. When power is off it releases the pin and a spring action closes the fuel inlet. If it is working you can hear it click when you turn the key on and off without the mower running.
Note: You may have to sit in the seat or push down on the seat to close the seat safety switch in order for the fuel shutoff to activate and be heard as it is hooked up to shut off when you exit the seat as a safety measure.
Note: You may have to sit in the seat or push down on the seat to close the seat safety switch in order for the fuel shutoff to activate and be heard as it is hooked up to shut off when you exit the seat as a safety measure.
Last edited:
jinman
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When solenoids fail, they normally short out completely and burn up or open completely and not work at all. The only thing I can imagine would be that your solenoid has some obstruction that could keep it from pulling in. If you are in contact with the shop, they should be able to tell you the coil resistance of the solenoid so you can measure it with an ohmeter. I would jumper 12 vdc directly to the solenoid plug when checking. I would NOT trust the ignition circuit to be good other than the solenoid's connector. Some solenoids have pull-in coils and hold-in coils, but I doubt the fuel solenoid on your LT170 is this sophisticated. My diesel truck with a Cummins engine is this way, but I don't think lawn tractors have reached this level of sophistication. Besides, I just don't see how the solenoid could cause your engine to operate if partially choked.
I'd think you might have a float needle valve that is not allowing fuel to fill the float chamber properly or a plugged orifice in your carb that is not allowing normal engine vacuum to draw fuel in through the main jets. When the choke butterfly closes, it increases the vacuum to draw more fuel from the float chamber while restricting the air flow. Your carb either has a restriction in a fuel line or there is an air leak causing loss of proper vacuum so that you have to increase it with the choke butterfly. Vacuum leaks are normally only a problem at idle when the engine will surge and run rough. When the engine is running at full speed, the vacuum leaks don't normally cause any significant problems.
Certainly, the electrical part of the ignition could cause the engine to run rough, but I would not expect choking the engine to improve that. I believe your problem is fuel related and the carb is most suspect.
I'd think you might have a float needle valve that is not allowing fuel to fill the float chamber properly or a plugged orifice in your carb that is not allowing normal engine vacuum to draw fuel in through the main jets. When the choke butterfly closes, it increases the vacuum to draw more fuel from the float chamber while restricting the air flow. Your carb either has a restriction in a fuel line or there is an air leak causing loss of proper vacuum so that you have to increase it with the choke butterfly. Vacuum leaks are normally only a problem at idle when the engine will surge and run rough. When the engine is running at full speed, the vacuum leaks don't normally cause any significant problems.
Certainly, the electrical part of the ignition could cause the engine to run rough, but I would not expect choking the engine to improve that. I believe your problem is fuel related and the carb is most suspect.