Wheel Horse Classis Won't Start

[John A 30]

Hi:

My Wheel Horse GT Classic Garden Tractor Model 73450 decides yesterday to not start.    It has been running fine all spring and summer up until yesterday.  It was parked in our barn for about a week.  The battery has been charged several times while I try to solve the problem.  The starter spins the engine well and everything sounds normal except for running.  I have no evidence of a spark or gas problem but today I did replaced the fuel filter and the spark plug.  As far as I can tell, all the wires are connected.

I bought the tractor, brand new in 2005.  This is very unusual.  The tractor has about 530 hours.  With the exception of a couple of batteries, a neutral starter switch, basic maintenance items, the tractor has been dependable.

I would appreciate any suggestions to solve the problem. 

Thank You,

John

[Ed Kennell 42,700]

Will it start if you spray some fuel in the carb?

[953 nut 61,318]

   There is a 10 Amp fuse connected to a Pink wire that provides power to the ignition kill relay, make sure the fuse holder is clean and the fuse is good.

[Lagersolut 745]

Check the safety switches under shifter plate and under the seat - I had one go bad about the same hours - tractor would just randomly shut off not start - it was a real bear trying to figure it out - could be a bad switch or a wire rubbed through - parking and reverse switch under the shift plate seat switch on the rear fender pan - I've had a wire rub through and a switch go south in 20 years - owned mine from new also . Throw a spark tester on it if you have one will help narrow down the search 

Edited September 28 by Lagersolut

[RED-Z06 2,628]

Most of the safety switches will prevent cranking (neutral, clutch, pto), if it cranks over fine, id give it a sniff of carb cleaner down the intake, if it lights off...you have a fuel supply or delivery problem.  If it doesn't, you have an ignition problem.  Coils do go bad.

[JoeM 8,633]

I had one in the shop a while back. If you find it is an electrical problem this may help. With all the safeties, I ended up making my own map. 

 

[clueless 3,315]

14 hours ago, RED-Z06 said:

Most of the safety switches will prevent cranking (neutral, clutch, pto), if it cranks over fine, id give it a sniff of carb cleaner down the intake, if it lights off...you have a fuel supply or delivery problem.  If it doesn't, you have an ignition problem.  Coils do go bad.

[John A 30]

Guys: Thanks for the comments and suggestions.

Today, I removed both of the 10 amp fuses from the fuse block.  These looked okay.  Just coved with some crud on top.  I wiped them off with a clean paper towel and replaced; NO Start.  Then these were switched to eliminate one being blown, NO Start.

After removing the air cleaner, I sprayed carburetor cleaner into the carburetor and tried to start the engine.  Again the same result, NO Start.  

I had ordered a spark plug tester and it arrived late today.  I connect it in line with engine ignition wire. There was NO spark in the tester window.

I guess it comes down to trying to eliminate the safety (?) switch that is preventing a spark.  I did take a look at the proximity (neutral starter) switch at the gear shift lever.  From the top it looks okay and is in place.  A few years back, its plastic bracket had broken.so it was just hanging in the area.  I ordered a new one and replaced it and everything was fine until the other day.  I cannot recall from that experience, if the engine would still turn over with a faulty proximity switch. Since it is only needed when starting the engine, I think there is a way to get around this switch for a test, but I cannot remember the details. Maybe a magnet would work.

Thanks again for your help in trouble shooting.   

John

PS- My 308-8 Wheel Horse is now carrying the load.

[953 nut 61,318]

19 minutes ago, John A said:

I guess it comes down to trying to eliminate the safety (?) switch that is preventing a spark.

Your safety switches are NOT preventing the ignition system from working.            Too many people rip out safety switches first and then find out what the actual problem was. They never hook them back up and endanger themselves and others.       DON"T DO IT.

 

You can TEST your seat switch with a multi meter set to Ohms, There are two wires connected it to the seat switch, unplug the seat switch and test the seat switch wires, with no weight on the seat there should be no continuity between these wires, with pressure applied there should be continuity.

You can TEST the Neutral (brake) switch. It has two wires going to it, with the key in the start position there should be 12 volts DC coming into the switch on the pink wire and 12 volts DC leaving the switch on the violet wire.

48 minutes ago, John A said:

10 amp fuses from the fuse block.  These looked okay.

How did they test with a meter?

[RED-Z06 2,628]

Pull the plastic engine shroud, pop the kill wire off the coil...if you still have no spark, bad coil.  If you have soark, start working back from there.

 

The shifter switch should be part of the start relay.  Put it in gear, clutch in, it shouldnt crank over. But as said..most of these switches have no connection to spark when cranking.

[JoeM 8,633]

John if the engine is spinning over, this means K1 (kill coil) is coming in.

If it is not starting the problem is in the magneto on the engine. Need to test the coil. 

[John A 30]

Guys, Thanks for the help.  The additional information should help me.

 

John 

[John A 30]

October 2, 2025

Guys:

Okay, I have found a serious problem with the Ignition module.  The high voltage wire which goes directly to the spark plug was gnawed off.  Probably by a mouse since I found a large nest under the engine shroud. 

I ordered a replacement module from a local parts dealer on Tuesday. It was supposed to arrive the next day.  After not hearing from the dealer I called and found the part was misplaced.  So now I need to wait for several more business days for a reorder from Granger.

  Anyone have suggestions for an alternative or faster shipment along with an approximate price for an OEM replacement?  The KOHLER engine is a CH15S, Spec 44533, Serial # 3506918161.  I was initially quoted a price of approximately $35. I am not sure of the price from Granger will be.  

Thanks for the HELP with the troubleshooting.  All the safety switches tested out as working.  Your help was invaluable to me.  Of course, the last thing I looked at, was the coil.  

 

John A

[Ed Kennell 42,700]

6 minutes ago, John A said:

r faster shipment along with an approximate price for an OEM replacement? 

er Will either of these work?    $10 each+ shipping

 

[John A 30]

The Part # listed on Part Tree is 12-584-04-S.

 

John A

[Ed Kennell 42,700]

I don't know what the difference is between the 01, 04, and 45 models.   Maybe someone will chime that can help.

[RED-Z06 2,628]

O4 and 01 should interchange, 04s is long discontinued 

[Lagersolut 745]

From Jacks small engines 

 

 

[Lagersolut 745]

The Jungle site also has an aftermarket alternative for $18 if OEM doesn't matter 

Edited yesterday at 10:29 AM by Lagersolut

[John A 30]

Guys,

My local parts dealer came through late this afternoon and found the misplaced module I ordered on Tuesday.  All the parts and switches are reinstalled along with the new module.  The tractor started immediately when I turned the ignition key.  It is running great.  It took me longer than expected to reinstall the metal engine shroud. 

 

Below are two pictures of the problem.   

 

I spent probably over an hour removing the grass all around the head of the engine using a vacuum.  I had not noticed the engine overheating but with all the grass and straw removed it should run cooler, 

Thanks to all for the advice. 

 

John A