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I have a Cub Cadet model 1515 lawn tractor with a Kohler 15HP Command CV426. I can't get the tractor to start. It wants too, when cranking the engine you hear it starting to lift away off the starter but when you let off the starter it dies.

I have fuel and spark. Here is what I tried:

- Confirmed spark by pulling the spark plug and cranking engine by holding the plug to the block. I can see consistent spark.
- Verified fuel pump is working as I had a full bowl of fuel in the carburetor.
- Verified fuel shutoff solenoid was working by connecting it to 9V battery.
- Cleaned carburetor.
- Replaced spark plug. Gapped to .040" per service manual.
- Replaced ignition module
- Replaced stator regulator
- Replaced carburetor with cheap amazon one

I have noticed it back fires out of carburetor and its way more pronounced after I put the cheap Chinese carb on.

My neighbor owned this tractor since new but gave up on it last summer and gave it to me. He had trouble getting it to start. I just put a new starter and battery on it and it fired right up. Then changed the oil, air filter, fuel filter, fuel line, and spark plug once I knew it would work. Its worked fine all summer for me until now. Any ideas? Thanks!

You need fuel,spark (at The correct time), and compression.
Have you checked the flywheel key?

Scrubcadet10 said:

You need fuel,spark (at The correct time), and compression.
Have you checked the flywheel key?

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Good idea. I check that again. I pulled the flywheel off once this summer and the key was fine then. I pulled it to clean the cooling fins since it was losing power on 90F days this summer when it got hot. Cleaning the engine fixed this issue. Ill look at this tomorrow. Thanks

It isn't a broke key either. Any other ideas?

I wonder if you have good compression?
Have you tried spraying starter fluid or carb cleaner in it and seeing if it starts?

Yes, I have sprayed starter fluid into the carb and it just helps towards flooding it. I suppose I could rent some gauges from Autozone and see if its low on compression. Do you know the compression spec for this motor? I may reclean the carb too.

Probably between 140 and 160 psi.
But since this engine has an Automatic compression release for easier starting it will be hard to get an accurate reading.
You should probably get at least 75 PSI with a auto compression release




And one more thing, you do have the correct oil amount in it,right?

Scrubcadet10 said:

Probably between 140 and 160 psi.
But since this engine has an Automatic compression release for easier starting it will be hard to get an accurate reading.
You should probably get at least 75 PSI with a auto compression release




And one more thing, you do have the correct oil amount in it,right?

Click to expand...

I tested it and got 40psi. I had the carb off though. But I didnt think that would matter since your suppose to open the throttle wide open. Im going to rent a different compression tool to confirm I didnt get a piece of junk from autozone. If so then I will debate if I feel like tearing it down for a rebuild if there are rebuild kits for this engine.

you do have the correct oil amount in it,right?

Sorry, forgot to answer that. Yes. The oil level was perfect and it didnt look like fuel is getting in it past the rings.

I tried another compression tester kit and this time I got 50psi. Also the gauge would hold pressure where the other one didn't so this leads me to believe the first gauge was leaking. Also, I really don't know how much I believe if I have good or bad compression from this because I was reading in the engine service manual that there is a ACR (Automatic Compression Release) mechanism that is there for easier starting. I know ScrubCadet you mentioned this already. The manual stated its better to do a leak down test. I don't have access to the tool, but maybe can come up with something after I research it.

So assuming I have compression. Im going back to the carburetor. Im going to soak the original in carb cleaner for a day or two and swap the needle and float from the China carb I got. See what happens after a really good cleaning. Also I noticed on the china carb has air cutouts in the flapper on the throttle valve. The original one did not so maybe that is why the new one will not work. If all fails still then, I will tear the engine down for fun and see what if might need. If there isn't anything alarming that is going to require a bunch of parts Ill buy a rebuild kit I've seen online for $100 and rebuild it. If I suck at that, then I guess Ill go buy a used mower for next season which I will make sure does not have a Kohler engine as maybe the lesson learned is they need to stick to making toilets and shower heads

I wouldn't attempt to swap the seat from the Chineseium carb.
You risk damaging it, and possibly flooding your engine
Then again I said I wouldn't attempt it

50 PSI, on a ACR, I usually get 80 with Briggs push mower 6.5 horse.

Start with nice new plugs.
Now spray a VERY SMALL AMOUNT of carb cleaner down the plug hole. replace the plug and crank the engine.
If it fires then the spark timing is good.
If it backfires out of the carb or exhaust you have a valve problem.

Assuming you get a bang or two, repeat but this time spray a VERY SHORT SHOT of carb cleaner down the carburettor throat.
If the engine fires then you have a fuel supply problem
IF not then you have a valve problem.

When it comes to using sprays, less is better than more.
If you spray too much then you can wet the plug and cause it to short so you get no spark.
I have seen people start to spray the gunk down the carb for near a minute before they hit the starter.
They then tell me "this shite never works"