Help Diagnosing Issue

Sounds like there may be a collapsing fuel line or something in the gas tank blocking the fuel port, causing it to starve for fuel.
 
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ChrisBFRPKY said:
And this. Once you get the engine bolted to the frame, check to make sure your engine has an adequate fuel supply. Check for loose debris in the tank, check to make sure the fuel pump is good and check for pinched off fuel lines. You have an obvious fuel starvation problem. I've read thru the thread and if you've made sure the carb is not the issue by cleaning all fuel passages then the issue is going to be a fuel supply problem.

BTW, the engine video of the one side overheated was caused by running the engine for an extended period without the fan shroud/blower housing. Any air cooled engine will overheat without that shroud/housing in place.
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I was thinking the same thing when i watched the video.
Be sure to check the fuel tanks for water.
Those amoebas of water will slosh around on the bottom of the fuel tanks and give intermittent run issues as it picks it up and digests it.
 
Try draining the fuel tank and looking at the connection between tank and fuel line. Your symptoms are very similar to mine and I found a debris (mud) plug in the elbow connection to the tank that was essentially allowing 95% of fuel demand so it took about 20 min to drain the carb bowl of fuel and then it would sputter and die. Playing around with the choke would save it for a little bit but would eventually die. Blade engagement puts more demand on engine and therefore burns more fuel and makes it worse. Possibly your air compressor did not dislodge a debris plug like the one I had… something to consider, at least.
 
Just a thought, although most of my work repairing is on Command series twins. Most suggestions is what Rivets suggested previously. It definitely sounds like a fuel issue to me. It was mentioned previously that the carb was cleaned several times. Did the jets and emulsion tube get cleaned during any of those cleanings? Also, was the fuel solenoid checked and cleaned? Any or all of these can result in lean condition. Also, to completely test the ignition coils, run it with the inline spark testers. Then when it starts running rough check each spark tester. It could be that one coil is failing when hot. Complete lack of power is the result.
 
I would tend to go after a coil issue, but one other thing you can chek. Sometimes the fuel lines will swell up inside and will look fine from the outside. The same problem occured on the short rubber brake lines on cars. It's not the gas that will break down the rubber on the inside of the hose, but some of the chemical in additives, to clean out fuel systems, will swell the inside of the fuel line restricting fuel flow. However when this happens it usually effects the engine hot or cold. Just a thought though, if you have tried everything else. Cintinue the fight and don't give up!
 
As far as testing fuel solenoid, it should have been removed for cleaning. The solenoid needle needs a good seal to stop fuel. You can bench test it by disconnecting solenoid wire then using a couple of jumper wires from a 12V source, connect negative source to the solenoid body and the positive source momentarily to the positive lead from the solenoid. The needle should retract when power to connected. If it retracts consistently the solenoid is fine. Use carb cleaner on the solenoid and carb port to ensure any debris or varnish is removed.
 
MrLarkins said:
First time poster here, thanks in advance.

I'm running a Husqvarna RZ5426 with a Kohler SV735 (Courage 26hp 725cc). I purchased it new years ago and have maintained it well. This season something has changed. Let me describe the symptoms and tell you what I've looked at already.

Symptoms:
  1. Runs a slight bit rougher than normally. By this, I mean that the engine shakes more than years past, but it isn't much.
  2. Starts fine and runs for a good 15 mins; Then the engine will wain when under a strain, to the point where it dies. This can be mitigated somewhat by disengaging the blades and releasing the handles so that it idles in neutral.
  3. If the engines does shut off, it can easily be restarted, but runs best if let set to cool down.
What I've looked into:
  1. I've checked the oil level; it is full but not overfull. Oil is clean from a recent change.
  2. There is no smoke in the oil fill pipe as would be the case if a head gasket was leaky.
  3. The carb was taken off, apart and cleaned. No trash was in it.
  4. Gas is fresh, and fuel filter was replaced last year. Fuel pump was tested and is pumping as it should.
  5. Air filter is new for the season and not clogged.
  6. Battery is 1 year old and holds at 12.8v.
  7. Spark plugs have spark. I did disconnect each spark plug momentarily to see if each cylinder was firing. I did this quickly so the engine wouldn't run too long...just a couple of seconds. Each cylinder ran fine.
  8. I cleaned the debris was the engine block fins, thinking it was a cooling issue. one side seems clogged with grass, but there was no oil leaks anywhere on the block, and I looked hard after taking covers off.
The only defect I did find was a crack in the muffler.

Okay, there it is. Any suggestions of what I should look into next?
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Worth checking the exhaust isn't blocked, easiest way is to remove it and try with ear defenders on.
 
Coils can go out when engine warms up. Check spark or cylinder activity when engine starts acting up. If it cools down coil most likely will start working again.
 
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