Engine won't run over an idle.

[peejo50 37]

I have a 312-Hydro with a 12 HP Kohler Magnum engine. I got it out to do some work and had it running for only a few minutes when it backfired and shut off. Upon trying to restart it, sputtering and backfiring re-occurred but it did start and ran at an idle for about 5 or 10 seconds. It will restart again but still only a short time at idle. Before I start tearing it down, I was hoping to get some input to help me out. Also, it says not to tow these hydros, but what do you do when it can't move on its own power?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                Update.

Okay, so I've gone through the fuel system. Checked the fuel pump and gas line, pulled and cleaned the carburetor. Made no difference. I switched the carburetor with the one from my C-120. Still no difference. 

Edited July 4, 2023 by peejo50

[Ed Kennell 35,904]

Sounds like it may be running out of fuel or on bad fuel.  Loosen the cap on the fuel tank.  If that doesn't help, pull the line off at the carb and have a helper crank the engine while you hold the line in a container.   You should see a good spurting supply of fuel.  If not, pull the line off of the fuel pump inlet and you should have a free flowing supply to the pump.  If not, pull the fitting out of the tank and clean the screen.

This tractor has the Eaton 700 hydro if it is manual lift or Eaton 11000 if hydraulic lift.  Neither have a tow valve and can not be towed without possible damage.    The Eaton 1100 can be pushed slowly by hand.  The Eaton 700 is very difficult, but may move if you jiggle the motion lever around nuetral while pushing by hand.

[CCW 1,206]

I had trouble with 312-8 when the choke linkage disconnected. 

[Darb1964 1,014]

If you can make some sort of a small lift, another tractor with bucket or three point hitch. Get the rears up just an inch or so and move it slow. Probably take two people.

[lynnmor 6,807]

1 hour ago, Darb1964 said:

If you can make some sort of a small lift, another tractor with bucket or three point hitch. Get the rears up just an inch or so and move it slow. Probably take two people.

We would tow dead snowmobiles by zip tying those cheap rollup sleds under the tracks, should work for dead little tractors, at least on grass.

[wallfish 15,946]

Not always easy but pull the hubs off and remove the key. Hubs back on keyless and take it slow towing it with someone watching the hubs. When they walk off, stop and push it back on all the way.

A hand truck layed down under lengthwise or use a moving dolly and drop the trans down on it by removing the the wheels?

Or do like a bunch do. Put a for sale sign and ran when parked on it.

 

Your latest Update kind of rules out fuel delivery. Time to hunt down the spark issue.

Had a similar problem like that which turned out to be the key switch intermittently grounding.

You can completely disconnect the switch by pulling off the plug to it. Use jumper cables directly to the starter to spin it. A magnum will run with nothing connected to it since it generates it's own spark. If it runs, key switch. If it don't, it's deeper into the ignition system we go.

 

Edited July 4, 2023 by wallfish

[peejo50 37]

1 hour ago, Darb1964 said:

If you can make some sort of a small lift, another tractor with bucket or three point hitch. Get the rears up just an inch or so and move it slow. Probably take two people.

I think my next project will be a tow dolly rather than a lift. My Power King has a 3 point hitch if I needed to move one of the Wheel Horse tractors but if I need to tow the Power King, I'd need a dolly. I maintain 6 acres and help my neighbor with his 15+ acres too. 

[peejo50 37]

5 hours ago, wallfish said:

Not always easy but pull the hubs off and remove the key. Hubs back on keyless and take it slow towing it with someone watching the hubs. When they walk off, stop and push it back on all the way.

A hand truck layed down under lengthwise or use a moving dolly and drop the trans down on it by removing the the wheels?

Or do like a bunch do. Put a for sale sign and ran when parked on it.

 

Your latest Update kind of rules out fuel delivery. Time to hunt down the spark issue.

Had a similar problem like that which turned out to be the key switch intermittently grounding.

You can completely disconnect the switch by pulling off the plug to it. Use jumper cables directly to the starter to spin it. A magnum will run with nothing connected to it since it generates it's own spark. If it runs, key switch. If it don't, it's deeper into the ignition system we go.

 

I have great spark at the plug.

[wallfish 15,946]

10 minutes ago, peejo50 said:

I have great spark at the plug.

Fuel solved

Spark good

 

Wonder if it's the key in the flywheel. The key sets the flywheel position for the spark timing.

 

[Ed Kennell 35,904]

Good fuel and spark.       That leaves timing, compression, and a clogged exhaust.

[peejo50 37]

Time to go out and start delving deeper into this problem. I find it hard to believe anything major could be wrong since it still continues to start, even if for only a short time.

[Ed Kennell 35,904]

Next easy step....remove the muffler.     No change, then go deep and find the bad exhaust valve.

Edited July 5, 2023 by Ed Kennell

[peejo50 37]

So reaching deeper into the problem I checked the flywheel key, removed and checked the muffler, pulled the cover and checked the gap on the tappets. All was as it should be. What I did next was to eliminate the ground wire to the mag. Low and behold it ran and even revved up. I mowed for about 15 minutes without any sputter or miss firing but it seemed to only be running at about 90 percent. I shut it off but had trouble starting it again. It would continue to run but it was a struggle to get it to rev without backfiring. At this point I can only figure that it must be the magneto. I can't understand how I could go from having the best mower ever to the worst nightmare with just a burp!

 

[peejo50 37]

Well, the problem has been resolved with the magneto replacement. Running like normal again. 

[ineedanother 1,365]

42 minutes ago, peejo50 said:

Well, the problem has been resolved with the magneto replacement. Running like normal again. 

Good deal. I wish I had seen this earlier but I was out of town. I might have suggested to run it in the dark, preferably with the  shroud off to see if it was sparking where it shouldn't have been. The mag might be fine, don't throw it away just yet...

[BESTDOGEVER 218]

I would hang onto the module as ineedanother said my experience is they are good or dead. Checking in the dark is a good idea still just to be sure there is nothing else going on. Maybe something too close to the ground on the module, thin spot on kill wire.