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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 27492
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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Curtis -- I'm back again with another question. My LX

Customer Question

Curtis -- I'm back again with another question. My LX 172 will start and run while in neutral but stops running when the transmission is engaged for either forward or reverse movement and also when the mower blades are engaged. Suggestions?
Submitted: 1 year ago.
Category: Small Engine
Customer: replied 1 year ago.
Safety switch under seat has been jumpered and also disconnected but with the same results. Engine stops when pto or gears are engaged.
Expert:  Curtis B. replied 1 year ago.

Run circuit shows a relay.

Expert:  Curtis B. replied 1 year ago.

K 1 relay. It is what shuts off the fuel solenoid. You could always remove the file solenoid! It is ant-backfire solenoid and really serves no other function, other than keeping engine from backfiring once when the key is turned off hot! Not used on older models.

Customer: replied 1 year ago.
The solenoid extends from the bottom of the carburetor and has a wire attached as I understand. I removed the wire first with no change to the problem. Should I remove the solenoid completly and plug the hole with a bolt?
Expert:  Curtis B. replied 1 year ago.

Unplugging the solenoid should keep engine from starting! It has to be removed or the inner parts removed to disable it.

Customer: replied 1 year ago.
The engine started with the wire disconnected. I will remove the solenoid and plug the hole.
Customer: replied 1 year ago.
I removed the solenoid and used a bolt to fill the hole. That didn't fix the problem. What next?
Expert:  Curtis B. replied 1 year ago.

Engine just has a coil and magnet in the flywheel to make the spark. Remove the kill wire from the coil and see if engine continues to run. If it does, the kill circuit is being grounded by safety switch. If not, the engine is just stalling and the carburetor and fuel supply are not passing the fuel. Engine is either losing fuel or spark.

Customer: replied 1 year ago.
Engine stops when wire is removed. Since engine continues to run until pto or gear shift is moved that should indicate that fuel is still flowing . What would stop the fuel?
Expert:  Curtis B. replied 1 year ago.

Engines stops when wire is removed? starts and runs, but still shuts off? Have you removed and cleaned te carburetor and check the flow to the carburetor inlet? This has the pulse fuel pump, so is the pulse line open to the crankcase and you feel the pulse if you remove hose and check with finger?

Customer: replied 1 year ago.
The safety seat switch was jumpered with no change in operation and the disconnected with the same results. That should have been an alert that the problem of keeping the engine running was connected to that wire bundle. After removing the parts covering that bundle I discover that the wires had been severed by resting on the v-belt pulley effectively acting as the safety switch for the seat when dismounting. Problem solved by cutting and tying wires together past the cut wires. The solution was missed by not following the observation that the engine kept running when the safety wires didn't respond to being connected or disconnected.
Expert:  Curtis B. replied 1 year ago.

Good job! Thanks for the update.