Kohler Cutting Out - Carb cleaning?

[Digger 258]

Thanks tmarks. So there's a chance it's not the switch, and since I have a certain ground at the fuel shutoff solenoid (the carb mount bolt), then it would be the solenoid itself. Hmmm.

I called PT yesterday right before they closed shop and ordered a manual (finally) and a replacement key switch, thinking that was the problem.

For now I will scratch my head and continue to shut her down by pulling max choke.

Thanks again!

 

[rswyan]

I'm in the process of cleaning the carb (Walbro) on a Kohler Magnum 18 in Simplcity CFC 18 (circa 1985 - 87)

I say "in the process" because I've had the carb off twice now ... and both times there's been black crud in the float bowl. I suspect fuel line deterioration after the filter.

Symptoms are the same as the OP's ... will only run with choke on.

Runs good after I clean it ... until more crud accumulates in the float bowl.

Just an update on this.

I ended up having to replace the fuel pump ... diaphragm and/or check valves were shot, in addition to the hoses being deteriorated ... crankcase was full of fuel.

Just something to be aware of ... even though mine is a Kohler Magnum 18.

 

[Marks481]

For now I will scratch my head and continue to shut her down by pulling max choke.

Wow, that does sound like you are not getting a good ground to the switch or your new switch is bad. DO you have a multimeter you can test it with?

In the engine compartment, there should be a 5 pin connector for the wiring harness going to the engine. The White wire from that goes to the magneto that makes the spark for the spark plugs. When the switch is turned to off, this grounds the magneto (see connection U below in the diagram), robbing the spark plugs of electrical current. This white wire should have an un-used female spade connector piggybacked (see J below); this is supposed to be hooked up to the oil low pressure switch (see B below) to shut your engine down if you lose oil pressure. PT likes to leave this switch unconnected. I don't.

So with your engine running, ground out this spade connector and see if the engine stops. That will tell you whether or not the problem is the ground for the ignition switch or the ignition switch itself.

btw, the fuel shut-off valve in the carburetor is energized to open while running, and when the key switch is turned off, voltage is no longer applied and it shuts. This is the red wire (X) in the wiring harness that goes to bleh carburetor (W). I was wrong when I previously said this was the same wire as the magneto ground.

I don't think the fuel shut-off solenoid kills all fuel to your carburetor (just to the main jet), so if the magneto doesn't ground out it may continue to run.

 

[Digger 258]

Tmarks, I am probably not alone in that I have a high dollar multi-meter, with a low dollar education on it. So far I managed to check continuity of the fuel solenoid ground by touching the negative battery terminal with one probe and the carb bolt with the other and my meter beeped, indicating continuity.

What you indicated about the white wire powering the magneto makes sense, so I'll start checking what's happening there and report back. I am pretty confident when I turn the ignition switch on, the fuel solenoid energizes and the plunger withdraws as it's supposed to. I think I've been hunting in the wrong forest on this one. It's gotta be the magneto still sending energy to the coil / plug. Thanks again.

 

[MossRoad]

... the white wire powering the magneto...

It's my understanding the white wire does not power the magneto. It grounds out (kills) the magneto when it gets switched to ground when the key switch is turned off. Someone please correct me if I'm mistaken. Thanks.

 

[J_J]

And my interpretation is, that once the magneto is grounded, it can not generate any more voltage and the solenoid shuts/closed.

 

[Marks481]

The White wire from that goes to the magneto that makes the spark for the spark plugs. When the switch is turned to off, this grounds the magneto (see connection U below in the diagram), robbing the spark plugs of electrical current.

Which is also how the low-oil shut-off works. Pressure sensor grounds that lead, shutting off the engine. Of course, PT doesn't like to hook that wire up for some unknown reason.

 

[Frank Sorbello]

Which is also how the low-oil shut-off works. Pressure sensor grounds that lead, shutting off the engine. Of course, PT doesn't like to hook that wire up for some unknown reason.

Moss, Is your low oil sensor hooked up on your Kohler?

 

[Digger 258]

Well, I got another new ignition switch from Tazwell, and once installed, everything works as it should. It starts great, runs fine and even shuts itself off when I turn off the key. I guess after coming full circle, it was my switch that was bad. Happy for the journey to get there though. thanks for all the help. I guess while I am at it, I should figure out how to hook up my low oil shut off as well. Take care.

 

[woodlandfarms]

I want to say that the low oil shutoff was disconnected because the PT can go sideways steeper and it posed issues with the machine. Could be WAY off on this... wouldn't be the first time for sure.