1987 310-8 key switch to plug match problem

[Armadillo👍 8]

With the 301991 switch installed the engine turns over but won’t start. The spark plug has a good strong spark. No start using starting fluid either. 
Since the push to start button by passes all the wiring I’m going to remove the 301991 start switch and hook the push to start button back like it was and see if the engine starts.

There seems to be good compression but I’m going to get a compression tester and test compression just in case.

[953 nut 67,944]

Compression tests on a Kohler with compression release can be a bit hard to go by. The cam shaft has a feature that releases some of the compression until the engine is turning over a couple hundred rpms to make it easier to start.

If it ran good before it shouldn't be a compression problem unless it was opened up or the valves adjusted. Even though the engine has good spark I would start with a new spark plug.        

[Armadillo👍 8]

I had forgot about compression release. It did run before. It has a new spark plug. Thank you.

Edited August 11 by Armadillo👍

[pfrederi 20,964]

I would put back the old plug that was in her when she last ran...Wouldn't be the first time a new electrical thing didn't work....especially if it is a Champion they fail to fire under compression

[sqrlgtr 3,547]

[Armadillo👍 8]

Finally got back to work on the Wheelhorse. Pulled the key start. Turned engine over with wire connection from battery to solenoid. Engine started. Yay!

Rechecked all the wiring and realized the ground wire attached to the 103991 switch wasn’t grounded.

Reading the diagram for 1987 301 models the ground wire from the key switch goes to the seat switch. The seat switch, when the seat is sat in, seems to not be grounded but the diagram shows another ground between the key switch and the seat switch. If that is true, is the ground for the seat switch controlled by the key switch??

Second question. It would be useful if the battery was charged when the engine is running. The diagram shows a ground and 1 hot wire for the battery. Does the battery charging circuit (if there is one) go through the key switch?

Thank you diagram reading gurus for your answers.

 

[gwest_ca-(File Mod) 12,410]

One side of the seat switch is grounded. With operator in the seat and the pto ON the switch is open so the magneto wire is not grounded and the engine runs. Operator leaves the seat the switch grounds the magneto and engine stops.

If the pto is OFF the magneto ground can not get to the seat switch so engine will run operator or no operator in seat.

[953 nut 67,944]

Your wiring on the 310-8 was designed for a battery powered ignition system and you have installed a Magnum in place of the old engine, is this correct?

The safety switch wiring for a battery powered system is different than that of a magneto system. With the battery powered system the safety switches remove voltage to the coil if you leave the seat with the PTO on. With a magneto system the ignition becomes grounded if the driver gets off the seat with the PTO on.

If you want to have your safety switches to work as they should the ignition switch socket needs to be changed back to the way it came from the factory, a 103990 switch and a kill relay installed or completely rewire the safety switches. Going back to the 103990 and kill relay would be much easier.

 

[Armadillo👍 8]

It’s clear that diagram logic is more difficult than identifying wires, tracing them out and testing for continuity.

If I understand correctly the diagram just shows the seat and key switch just have a common ground.

The diagram answered my second question because with the key switch in the run position has the battery terminal and rectifier terminal connected. I may be slow but I get there.

Thank ya’ll again for all the help!

 

[Armadillo👍 8]

The Wheelhorse was bought with the Kohler 14 in it.
The model number decal says 2010K804   indicates it’s a 1987. The other number on the decal next to the model number is 22694. I suspect there was a sn on a blank place on the bottom of the decal but it is gone.

Is there anyway a 1987 model could it originally have come with a Kohler Magnum 14? 

Naw. I had to change the original key switch plug wiring was for a different ignition key switch. Hmmm

Will need to think on if I want to go back to a different key switch so the seat switch will work. Haven’t tested that.
In testing so far the deck cut out switch works and prevents starting if the clutch is engaged with clutch handle in forward position.

[953 nut 67,944]

10 hours ago, Armadillo👍 said:

It would be useful if the battery was charged when the engine is running. The diagram shows a ground and 1 hot wire for the battery. Does the battery charging circuit (if there is one) go through the key switch?

Since we have determined that your engine has the 15 amp three wire charging system the drawing in your manual is incorrect, use the drawing below. As shown the charging does go through the ignition switch and a fuse.

OK, the 21-10K804 is a 310-8 from 1987 and came with a magnum engine. The 400 series offered a 14 HP engine but the fundamental electrical system is the same. The 400 would have had some idiot lights and a parking brake switch and light along with a bunch of otherwise unnecessary wires to feed the idiot lights.

Looking at your drawing of the key switch socket in the first post I figured it had been a battery ignition, no telling what a previous owner did. That is in the past, lets see what we can accomplish in the future.

The Seat Switch for a magnum is open with the operator in the seat and closed when you get off. the black wire goes to ground and the orange wire goes to half of the PTO switch as shown on drawing 7-13 of the attached manual. There should be a blue wire on the other terminal of that half of the PTO switch.

Check these out and we will continue figuring this out one step at a time.

 

 

[Armadillo👍 8]

Thank you for the link to the file!

The Wheelhorse was bought with the Kohler m14 in it when I bought it a couple of months ago. Who knows what was done to the electrical system besides taking out the key switch and installing a push button switch?

Checking the seat switch, it does have an orange wire going to the pto interlock and a black wire. The black wire is routed to the area behind the key switch and has a female terminal so I will connect it to the key switch ground terminal.
That seems to conflict with the diagram that shows a grounding point between the key switch and the seat switch. The key switch itself is grounded so that may take care of grounding the seat switch.
There are 2 black wires routed next to the key switch combined in a single female connector. 1 wire is bolted to chassis and the other goes to ground the volt meter. There is no place to connect the single female connector in the area that I can see so I suspect it went to the optional hour meter that I don’t have.

 

 

The orange wire has a blue wire opposite the orange wire at the pto switch. 

 

This is possibly another rabbit hole. There is a push pull switch to the left if the head light switch that has nothing connected to it. 

[gwest_ca-(File Mod) 12,410]

On 8/18/2026 at 3:00 PM, Armadillo👍 said:

The Wheelhorse was bought with the Kohler 14 in it.
The model number decal says 2010K804   indicates it’s a 1987. The other number on the decal next to the model number is 22694. I suspect there was a sn on a blank place on the bottom of the decal but it is gone.

Is there anyway a 1987 model could it originally have come with a Kohler Magnum 14? 

Naw. I had to change the original key switch plug wiring was for a different ignition key switch. Hmmm

Will need to think on if I want to go back to a different key switch so the seat switch will work. Haven’t tested that.
In testing so far the deck cut out switch works and prevents starting if the clutch is engaged with clutch handle in forward position.

22694 is the serial number.

The blank box below it has lost it's 4-digit Julian build date.

Recorded serials so far for the model and year range from 20051 to 24472