I am still having occasional problems with my Craftsman Mower. It runs great for a while and then sputters and dies.

Cold starts great. Runs great for a while then it will sputter and die. I cleaned the carb out, tested the fuel shutoff solenoid and flushed and cleaned the tank and lines. All looks well. It has a new fuel filter. Oil and filter are also new.

After I have run it for a while it will just sputter and die. When it does this the fuel filter looks almost empty but I think that is a red herring. If I disconnect the fuel line at the carb fuel flows great.

If I wait a few minutes and restart it runs great.

What could there be in this machine that is temperature sensative and could cause it to die like this?

It is a Kohler 16HP OHV without the mechanical fuel pump.

Thanks guys.

 

Ignition module or magneto most likely.

 

This is probably wayyy out in left field, but is the gas cap venting properly? Is there any chance it could be causing a partial vacuum in the gas tank after a few minutes of running?

 

Very often the cause of starting fine then quitting when the engine gets warm.
I would also check the valve clearance. It is adjustable on these overhead valve engines and they do go out of adjustment.
If you give me the Spec number of the tag on your engine I can tell you what the clearances should be.
Here is the link to Kohler's free downloadable repair manuals. Kohler Engines: Owners & Service Manuals: Manuals & Maintenance

When it restarts, does it remain running fine for as long as you need it to or does it quit again?

 

Might help to put an inline spark tester on it before using it the next time. Easy way to track down if the ignition coil is failing..

 

You might also try removing or loosening the gas cap, as the engine could be vapor locking on you.

 

Thanks for all of the suggestions. I think I have ruled out the gas cap after this issue first started last year. I cleaned the cap and filled the tank with water and it flowed beautifully out the gas line with the cap on until the tank was empty. I have also had the problem occur when the cap is off/loose.

Ignition problem sounds feasible. Let me throw in a few more things that may or may not be related. I didn't include these before to try to keep the clutter out.

1. The battery died this summer because of the drought and not having to cut grass for two months. I jump start it now and the battery doesn't seem to be charging.
2. The ammeter doesn't work anymore. It worked fine before the battery died.
3. I can run it straight for an hour (as I did today) and it will die. Wait 15 minutes or so and I can get another hour out of it, sometimes more.
4. When it is hot and I try to restart it with the battery charger on it, the starter can't overcome the compression stroke. Even turning it by hand is difficult. Often, if I can turn it past TDC it will start with the eletric starter.
5. Sometimes, if I run it for a while and shut it off then the battery will start it up fine.

Like I said, not sure if any of this is related but sometimes the dumb clues give the answer.

Sure do appreciate the ideas and information. ckal - I will get that number tomorrow. And thanks for the repair manual link. Will be downloading that now.

Thanks.

 

I am willing to bet that, perhaps among other things, you will find that your valves need adjusted. These smaller OHV engines use solid lifters as opposed to hydraulic lifters that require no adjustment. The difficulty in overcoming the compression stroke on OHV engines is often caused by too much space between the rocker arm and valve on the exhaust valve, thus rendering the compression release ineffective.

 

My Kohler engine is a 1995, 22 H.P. and it has hydraulic lifters and it needed new coils and a spark advance module to fix the same problem. Best, CB

 

I was kind of excited hoping a quick valve adjustment would help but lo and behold, my lifters are hydraulic.

My engine is a Kohler Command - I couldn't find a plate on the engine.

 

Offhand, I can think of two possible solutions.

1. Mow faster so that you're done before it dies the first time.

or

2. After the first hour, when it dies, use those 15 or so minutes of cool-down time to go get a beer or two. Then finish mowing.

Jason

 

Well then, that pretty much rules out valve adjustment.
I'd look to the ignition system at this point.
If you have a good spark plug handy, keep it in your pocket next time you mow. When the engine quits, pull a plug wire off one of the plugs and snap the plug from your pocket into the wire. Carefully hold the threaded portion against the fins on the engine (or any other good ground) and turn the ignition key. You may be able to do this without a helper if your tractor will start without someone in the seat when the parking brake is locked on and you can reach the ignition switch and the plug wire at the same time.
This is not the best way to test spark strength, but it will tell you if your ignition is not firing.
If your ignition is firing, you should see a spark across the electrode gap.
There is no silver sticker anywhere on the engine with a model and spec number on it? Maybe if you give me the model number of the tractor I can figure out exactly which engine Sears put on it.

 

A timing light worked pretty good for me. Best, CB

 

The tractor is an LT1000 if that helps. I bought it in 2002. The only thing I can find on the motor is Kohler Command 16 HP OHV.

I am going away for a few days but I will definitely report back once I run it again and try the spark plug test.

Thanks again everyone.

 

Probably under the seat on the fender, on the bottom of the seat itself, or perhaps on the underside of the hood should be a sears sticker.
The model number should read 917.XXXXX (not sure how many digits after the "917"