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Terry_Hart

Kohler ch18 shuts down

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Terry_Hart

It stsrts well cold, runs for 15 mins then stops. Almost like I shut it off. Shut the deck (pto) off and restarts fine. Then sometimes it will run for about a minute, and other times it will run for 10-20 mins?

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Terry_Hart

Ok, tried the vent. I removed the cap started it up and let it run, after a few minutes it shut down. I restarted it and let it run again and it shut down again. There is plenty of fuel in the filter. There doesn't seem to be any air in there. Not sure now if I have a fuel issue or electrical. I still think it is fuel, as it usually backfires if I shut it down at anything over idle.

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Terry_Hart

I think after seeing some youyube videos that I need to look there next. I have no experience with them. Not sure how to get to it, looks like the carb is behind the muffler. Do these ever fail or get week?

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PhanDad

I'd bet on a failing interlock module or something to do with it.

If you have a multimeter, hook it to the kill wire at the engine electrical connector (white wire) see if it goes to ground when problem occurs.

Another option would be to start the engine, then disconnect the engine electrical connector. I'm pretty sure the engine should keep running since it's a magneto ignition and the fuel solenoid should stay open by the voltage produced by the engine. If you do this, NO SAFTIES WILL WORK AND YOU'LL HAVE TO KILL THE ENGINE MANUALLY - by manually grounding the kill wire at the connector or hooking the connector back up so the ignition switch kills the engine.

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PhanDad

As BLT suggested, the carb solenoid valve wiring can be accessed by taking the air filter and the tin on top of the carb off:

IMG_4689a.jpg

:

IMG_4690a.jpg

The above pic has manual throttle and choke controls mounted in the way. Here's a pic with the blower housing removed so you can see better::

IMG_4694a.jpg

Without the manual controls, I think you'll have a clear shot at the solenoid/wiring.The engine electrical connector is on the right side of the engine, above the starter. It may or may not be mounted to the tin as in this pic:

IMG_4817a.jpg

Yours won't have the looped white kill wire (this wire was added by me to take an oil sentry out of the circuit if I wanted to).The interlock module is buried behind the battery, under the dash top plate.

IMG_4689a.jpg.d953c6e96dbbaf8e09e55de81541bc29.jpg

IMG_4690a.jpg.1515433242ee58fb3c14b8e39b883157.jpg

IMG_4694a.jpg.e4dbb35279bea2ebef05aee10d5e79e7.jpg

IMG_4817a.jpg.9134024beaff1dbdc6105c07fdc5152f.jpg

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PhanDad

The first 3 pics were with the engine out of the tractor.

By "shroud", if you mean the blower housing, I don't think so. As I said, your engine should not have the manual horizontal levers blocking the carb.

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powerking_one

Terry, you need to do basic troubleshooting "101" here. Are you loosing spark/ignition or fuel/fuel delivery? As a simple test, when the engine quits, have a can of starting fluid handy and spray of shot of it down the carb and see if it fires off. If so, then pursue the fuel system. If it is a no spark issue that is also very easy to test. You could use one of the types below:

http://www.ebay.com/itm/GK500-Portable-Automotive-Spark-Indicator-High-Intensity-Ignition-Tester-allsun-/262146100788?hash=item3d09200e34:g:TdsAAOSw1ZBUt3X1&item=262146100788&vxp=mtr

http://www.ebay.com/itm/Spark-Plug-Tester-Ignition-System-Coil-Engine-In-Line-Auto-Diagnostic-Test-Tool-/231101666038?hash=item35cebb92f6:g:xQYAAOSw-jhUFKTn&item=231101666038&vxp=mtr

Tom (PK)

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Terry_Hart

Thanks for all the suggestions! Here is where I am with it now.

- I took the air filter and the sheet metal base off.

- listened for the click of the solenoid when the switch was turned on, clearly audible

- Took the fuel line off the filter tank side, good flow. Into a glass, no water.

- connected the fuel line back up, then disconnected the line after the ffilter, good flow

- then I started it up and let it run, while I stood by with a spray can in case it stalled, to rule out fuel. It ran for over 30 mins.

- I put the air filter back together while it was running.

- then it shut down.

- when I tried to restart it, nothing not even a click when I turned the key

- I kept turning the key on and off several times. A couple of times it sounded like the starter clicked.

- I took the dash off and pulled the plug off the key switch, it was all gunk! I blew it out and plugged it back in, turned the key and it started.

- while it was running I wiggled every wire I found. It stayed running.

Shut doen for the night now, perplexed!

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Terry_Hart

Thanks for all the suggestions! Here is where I am with it now.

- I took the air filter and the sheet metal base off.

- listened for the click of the solenoid when the switch was turned on, clearly audible

- Took the fuel line off the filter tank side, good flow. Into a glass, no water.

- connected the fuel line back up, then disconnected the line after the ffilter, good flow

- then I started it up and let it run, while I stood by with a spray can in case it stalled, to rule out fuel. It ran for over 30 mins.

- I put the air filter back together while it was running.

- then it shut down.

- when I tried to restart it, nothing not even a click when I turned the key

- I kept turning the key on and off several times. A couple of times it sounded like the starter clicked.

- I took the dash off and pulled the plug off the key switch, it was all gunk! I blew it out and plugged it back in, turned the key and it started.

- while it was running I wiggled every wire I found. It stayed running.

Shut doen for the night now, perplexed!

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Terry_Hart

Stopped by the dealer, they suggested the circut breaker behind the battery and the seat

Switch. They said the citcut breakers get corroded and break apart. The circut breaker looks clean and intact. The switch under the seat was bypassed before I got it from them. I will check that next.

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PhanDad

Seat switch makes sense, but it's bypassed so it should be OK. Just make sure the bypass contacts are clean and making electrical contact.

I don't believe the circuit breaker could be the cause of your problem unless the engine's charging system isn't working. Obviously the CB isn't the problem for cranking since you can crank the engine. Running, even if the CB opened disconnecting the battery from the system, the charging system would keep +12v to keep the fuel solenoid open and the interlock module (IM) powered. I would think the logic in the IM would be "fail-safe" such that if the IM lost power, it would ground the "kill" wire to shutdown the engine - however I don't know if that's how it works.

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simple_stan

Sounds like the kill function of the control module is failing. You can disconnect the kill wire for troubleshooting. Just be ware that you will have no safeties until the kill wire is reattached. You should be able to see what I am referring to if you have a wiring diagram for the mower

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PhanDad

Here's the wiring diagrams, first with the Safety Start/Operator Present wires darkened:

Command_Safety_Op_Present.JPG

With the Ignition/Kill wires darkened:

Command_Igniioin_Kill_Wire.JPG

You can see how much more complicated the "safety start" (crank) circuit is compared to the "kill" circuit. Note the interlock module (IM) provides the ground for the "start" circuit as well as ground to kill the engine when running if the safety logic isn't followed. I believe when your tractor's IM gets warm after being powered for a while, it fails and shuts the engine down. I believe you said sometimes the tractor won't crank immediately, but will a short time later. My thought is the IM won't make the "start" ground until it cools down and functions properly again. The IM acting in this fashion has been posted about before.This is why the (IM) is suspected as the cause.

Command_Safety_Op_Present.JPG.830fa3f02a626b09e1ff040045fd4451.JPG

Command_Igniioin_Kill_Wire.JPG.1485c0568c3986d32a67ee7ae64667c3.JPG

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PhanDad

It could be the ignition switch. If the "M" terminal goes to ground when the key is in the "run" position, this would kill the engine. But it would have to be intermittent, so I doubt this is the problem. Since it sounds like you have the back of the dash open, you may want to take the IM out of the circuit for testing (or permanently) rather than disconnecting the engine connector after the engine starts. If you disconnect the IM , you'll have to put a jumper between the 2 black wire connectors as shown in blue:

Command_Igniioin_Kill_Wirea.JPG

This jumper replaces the jumper shown (black) that is on the IM side of the connector.

Command_Igniioin_Kill_Wirea.JPG.6e9c9a3074f00a61c4bc0414cc916d93.JPG

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HubbardRA

If the valves are too tight, as the engine warms up and the valves expand in length it will die when the valves stop sealing. It will cool down enough to re-start rather quickly. The longer it cools, the longer it runs till it quits again. I have fixed several engines that had this problem.

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MikeES

Check or by-pass the circuit breaker. I helped a friend diagnose a bad/weak circuit breaker with a CH-18, would do the same thing...run for awhile and then quit.

It could only handle a few minutes of charging going through the breaker and then trip, it would reset in just a few seconds. So the engine would start back up.

Replaced the breaker and no problems since.

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Terry_Hart

Update on my progress,

Replaced some of the cheaper items

Ignition switch

Voltage regulator (was charging at 18-20 amps) now about 4

New fuel filter and fuel line with tank grommet

Shortened and verified the connection for the bypassed seat switch.

Ran it for over 30 minutes without issue. There was no load on it, hopefully I will have some time to run it this weekend.

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