1863 electrical switch testing techniques

[wwesterfield]

Set out to mow the yard this afternoon. Tractor wouldn't start. "PTO Engaged" led was on at turn of ignition key, I checked the pto switch and it was off. After a couple more cranks the tractor felt like the pto was trying to kick in during cranking preventing the tractor from getting a full crank and starting. The battery became low from the load. I tried it a couple more times then the the ignition switch gives me nothing. No crank, no noise, no lights. Fuse is still good. pulled both the pto switch and ignition switch to put them on my tester. I am getting continuity through only a couple of tabs on the ignition switch and the same on the pto switch (i didn't for get to turn key) Is it possible that both these switches went bad at the same time?

 

[rbedell]

I would start with the PTO Switch first. I doubt that both the PTO and Ignition Switches went bad at the same time.

Sounds like the terminal B & A are stuck in the "on" position.

 

[wwesterfield]

turns out the pto switch was ok. The ignition, for whatever reason just gave up on me. Engine starts now with new switch but is missing horribly and something is still kicking in and loading the engine down heavily on start, about every 10th revolution during cranking something is kicking in and dragging the engine way down enough to stop the cranking. Narrowed the missing down to the left cylinder (as i am sitting on the mower) I replaced the plugs and runs just a pinch better but still really rough, really jurking to a stop. The mower ran perfectly two weeks ago when I put it in the garage. any idea?

 

[jdiederichs]

Wesley,

Did it backfire when you put it away last time? If so that may be the problem; a sheared or partially sheared flywheel key is messing up the timing. That would explain the loading of the starter and poor running. It would still have spark, just way out of time now. You'd need to remove the flywheel to examine the key. Should replace the key using a Kohler part, not a "will-fit" key.

You may also have a failed/failing ignition module on the left side, most dealers have the ignition module tester to "bench test" it. In the mower it can be tested using a special Kohler 18kv spark tester that goes on the plug wire.

 

[wwesterfield]

yes, I have accidentally let it backfire a couple of times by not letting it idle long enough before shutting down but that is the only time it has backfired. oh I really hope its not the key. I have to take it down again. I replaced the rear main seal when I purhcased it. was fun but time consuming. When I put in the new plugs it ran better. will talk to my small engine buddy to see if he has a tester I can borrow.

 

[wwesterfield]

jim, you are a genius. flywheel key was sheared. what is the torque on the flywheel bolt? don't what to put it on too loose and have this happen again.

 

[jdiederichs]

49 ft/lbs. Run engine a few secomds and retorque. Glad you able to find and fix it!

 

[jdiederichs]

The 1863 has a fuel solenoid on the main jet of the carburetor to eliminate backfires if used correctly. The procedure is to turn off the key ONLY with the throttle at/above 3/4 throttle, not at idle. Here is why:

The solenoid closes the main jet when the switch is turned off. With the throttle at the 3/4 open position, no fuel will be drawn into the hot engine because the open throttle won't create enough vacuum to pull gas through the idle circuit, and the main jet is held closed+ no backfire. Simple as that, and it does work well.

Older engine designs w/o the fuel solenoid used to like to be idled down; this all changed with the newer engines. They must follow the procedure listed above to avoid backfires which can shear flywheel keys, damage exhaust systems or even blow out a head gasket.

 

[tsmoker]

Jim,

I have a single cylinder Command in an off topic tractor that would backfire every time if I shut off at 3/4 throttle. I have to let it idle about a minute or so and then it is fine.

 

[jdiederichs]

Tom,
Many of the single cylinder Commands were built w/o the fuel solenoid carbs, depending on what the OEM wanted, so that is quite possible.

 

[tsmoker]

Mine does have the fuel shutoff solenoid. Just seems odd that it is different.

 

[jdiederichs]

Tom, It probably failed "open" due to corrosion etc. That happens. If you doubt what I am saying about the 3/4 throttle position, just check the op. manual, it'll confirm it. I know, it took alot of getting used to for us to change, we all grew up using the slow idle method, same on the farm tractors, right Denny?

 

[tmarkle]

Jim,
One thing I'll add about shutting them down; It is still a good idea to idle the engine for a minute or so to cool it down. Then open the throttle back up to 3/4 and shut it off.

 

[tsmoker]

Jim,

I am not doubting you. The manual does state half throttle. I just can't shut mine down that way. It is not the solenoid because the carb is new. It acts the same as the old one. The solenoid broke on my old one. I ran the old one with the plunger on the solenoid cut off for a while and I did not notice any difference. I am just throwing my experience with my tractor out there. I am not trying to contradict anyone.