Kohler Courage surging issues

[hamiltzp]

Hello,

I have several issues with a Troy-Bilt Bronco with the Kohler Courage 20 (SV600S) engine. This riding mower was purchased new in 2011.

When it starts, it gives a single crank and then pauses several seconds before cranking a few times again and starting. Once started, it surges about once a second. Sometimes it will even out for a few seconds, but then it goes back to surging. It sounds like it's running rough, and even when I turn it off, it seems like it shuts down rough.

While the battery is a few years old, I don't think that's really my issue. I gave the engine a complete service this season - new air filter, new gas filter, oil change (synthetic 5W30) with filter, and new spark plug. No difference. Based on some stuff I read, I also adjusted the valve lash to .005" on the intake and .007" on the exhaust per the service manual. No difference. I've heard that some guys adjust the valve lash to smaller gaps, but I don't want to go chasing my tail if that's not it.

Most of what I know about small engines is from YouTube University, so I am not an expert by any means. I thought I'd run it by this group and see if anyone has any thoughts.

Thanks!

 

[cptbarkey]

check for air intake leaks, try spraying brake cleaner/carb cleaner around the air intake, if it evens out you have a leak.
otherwise you are probably overdue for a carb cleaning, bad gas, rotten gas, putrid gas, water contamination.

 

[SwampSurvivor]

I went down this road with mine. It was surging bad and having issues but somehow running. VERY hard to start. I didn't have to check the valve lash since the command has hydraulic lash adjusters.

I don't remember the sequence of events but it ended up hydrolocked with fuel one day. It cranked over a half of a revolution and that was it. The float in the carb was stuck and it just drank a BUNCH of fuel while it was sitting.

Pulled the carb off (previous owner said it was a cheap chinese carb) , freed up the float and then it wouldn't run at all for more than a minute. I bought a new Chinese carb for it and it still wouldn't run for more than a minute until the bowl ran dry. Turns out the fuel pump failed.

I think the bad float was causing it to get too much fuel which kind of made it work because it was able to get enough fuel to compensate for the fuel pump.

I bought a Kohler fuel pump for it and now it fires off as soon as I hit the key and doesn't surge in the least.

 

[hamiltzp]

I don't remember the sequence of events but it ended up hydrolocked with fuel one day. It cranked over a half of a revolution and that was it. The float in the carb was stuck and it just drank a BUNCH of fuel while it was sitting.

Maybe, but I'm not sure. I forgot to mention because it's been a few years, but I had to replace the carb about 2-3 years ago because it leaked gas, and eventually stopped working entirely. It surged before that, and it surged after that. It wasn't hard to start and didn't run so rough back then, though. It's only been the last couple seasons that it is also hard to start and has started running rough.

 

[hemitom]

Have you checked compression ? maybe bad valve ?

 

[hamiltzp]

check for air intake leaks, try spraying brake cleaner/carb cleaner around the air intake, if it evens out you have a leak.
otherwise you are probably overdue for a carb cleaning, bad gas, rotten gas, putrid gas, water contamination.

Sorry for the stupid question, but how do I do that? Just take off the air filter and spray the carb cleaner in there? Also, how can I clean the carb wihout taking it apart? Would some Marvel Mystery Oil or something else help?

Thanks.

 

[hamiltzp]

Have you checked compression ? maybe bad valve ?

I don't have a guage. Is there any other way to do it?

Thanks.

 

[hemitom]

Accurately without a gauge not that I'm aware of.

 

[Rand]

sounds like an air leak or carb problem.

How much is a carb for it? might be worth it.. if its cheap.

Also is this gravity fed fuel tank.. with no fuel shutoff valve? add a shutoff valve if so.

 

[hamiltzp]

sounds like an air leak or carb problem.

How much is a carb for it? might be worth it.. if its cheap.

Also is this gravity fed fuel tank.. with no fuel shutoff valve? add a shutoff valve if so.

I had to replace the carb about 2-3 years ago because it leaked gas, and eventually stopped working entirely. It surged before that, and it surged after that. Not saying I don't have a carb problem, but I guess it's not at the top of my list at the moment.

Pretty sure it's a gravity fed fuel tank. A guy who did maintenance on it several years ago put a shutoff valve on it.

So can I just take off the air filter and spray carb cleaner in there? And if it smooths out, it's an air leak?

Thanks.

 

[cptbarkey]

I had to replace the carb about 2-3 years ago because it leaked gas, and eventually stopped working entirely. It surged before that, and it surged after that. Not saying I don't have a carb problem, but I guess it's not at the top of my list at the moment.

Pretty sure it's a gravity fed fuel tank. A guy who did maintenance on it several years ago put a shutoff valve on it.

So can I just take off the air filter and spray carb cleaner in there? And if it smooths out, it's an air leak?

Thanks.

Check the gaskets in between the air intake - carb - to the engine. if any are torn (or missing) that could cause surging with an air leak. Spraying carb cleaner/brake cleaner will get through those gasket gaps for confirmation. Cracks in plastic or aluminum could do the same thing.

 

[demarpaint]

After confirming the gasket mounting it to the engine is OK, I'd try dropping the carburetor bowl and spraying carb cleaner up the fuel pick up tube and make sure it's clean inside the carburetor. Then mix some B12 into fresh gas and run it.

 

[JTK]

Sounds like a plugged carb jet or corrosion in the carb. I'd put a new replacement carb on it and go from there.

Assuming this is a single cyl Kohler Courage, these used to have problems with the bolts under the flywheel loosening up that hold the crankcase cover on. Eventually you'd get enough wobble on the flywheel end of the crank that this would destroy the engine. Vibes and rough running were the initial symptoms.

 

[Brian123]

I had a neighbor who had this engine on his Cub Cadet Riding Mower with 900 hours on it and the last year he had it, the mower would surge, there is a gasket that is going bad, take the carburetor off and check the gaskets. Eventually the engine just crapped out, probably from getting unfiltered air or too much air. A valve went on the engine, maybe the exhaust valve.

 

[The_Eric]

Does it smooth out with the blades engaged?

Pull the plug and post a pic if you're able. The two things that come to mind are fuel calibration (since you said the surging prob precedes the replacement carb) and governor adjustment.

 

[spasm3]

Does it run ok on some degree of choke?

Use the red tube and spray carb cleaner around where the carb is bolted to the block. If the rpms increase, it's an unmetered air leak. If the rpms don't change the problem is probably inside the carb.

 

[hamiltzp]

Does it smooth out with the blades engaged?

Pull the plug and post a pic if you're able. The two things that come to mind are fuel calibration (since you said the surging prob precedes the replacement carb) and governor adjustment.

Good question. I hadn't thought about that. I haven't mowed yet this season, and I don't really remember. What would it mean?

 

[hamiltzp]

Got a question - I know I need to set valve lash on the compression stroke. Should I be setting valve lash at top dead center, or just past TDC?

 

[The_Eric]

Good question. I hadn't thought about that. I haven't mowed yet this season, and I don't really remember. What would it mean?

If it smooths out under load then I'd wager that the pilot circuit is too lean. It may take an adjustment of a needle or removal of the pilot jet and a little massaging with a pin drill. Usually if it's just a lean pilot, then .002"-.003" will cure it. To get it right you'll have to figure out the diameter of the jet, then calc the area and add about 10 to 15 percent to clean up that circuit.

This of course is after you verify no leaking gaskets or seals.

 

[The_Eric]

Got a question - I know I need to set valve lash on the compression stroke. Should I be setting valve lash at top dead center, or just past TDC?

Just a hair past TDC to avoid interference by the compression release