2 yo Husqvarna runs very rough

[TxFig]

About a month ago I was helping a friend clean out the home of his uncle, who had passed away ~4 months earlier. The estate had been settled and everything left in the house was "up for grabs" - including a 2 yo Husqvarna 46" riding mower (20 HP Kohler engine).

The little "hours indicator" shows it has 56 hours of use.

The first thing I did when I got the mower home was to drain the gas tank, change the fuel filter, and pull apart the carb (it was pretty clean). I put a new battery on it (since the one it came with wouldn't hold a charge).

After reassembling it, the mower started up and I mowed the back yard (about an hour). The engine seemed to run fine - but had less power (ALOT less) than the 21HP yard machine I've had for 7 years.


This weekend I went to mow again (texas, grass grows fast). This time it wouldn't start (turns over just fine - just no "fire"). So I pulled off the carb and look at it -- still looks pristine. Put it back on and spray in a bit of starter fluid.

Engine would fire and start with the starter fluid, but die very quickly. After doing this for ~30 minutes, the engine finally caught and would continue running....

very, VERY roughly. It has even less power than before (comes close to stalling when I engage the blade). It sputters constantly while running, and even backfired when I turned the engine off.



I'm stumped. I don't even know what to look for.

 

[ILENGINE]

Either something has come loose and got in owe of the carb jets or maybe it is running on one cylinder which could explain the low power, sputtering, and the afterfire.

 

[TxFig]

When I removed the carb, the jets seemed to let stuff go through fine (blew carb cleaner through it).

How would I check to see if it's only running on one cylinder?

 

[twinfords]

pull one plug at a time and see if there is a difference.

 

[TxFig]

I'll have to do that Friday night - I have to umpire softball games tonight.

 

[ILENGINE]

Just ground out each plug one at a time and see if the RPM's drop then that plug is firing, if no drop then no fire on that cylinder or if the engine dies the other plug isn't firing.

 

[ILENGINE]

Just ground out each plug one at a time and see if the RPM's drop then that plug is firing, if no drop then no fire on that cylinder or if the engine dies the other plug isn't firing. Could of also dropped a push rod on one cylinder. would have compression but no power output.

 

[TxFig]

Turns out that this model of mower / engine only has 1 spark plug. When I pulled it and cranked the engine, I didn't see it sparking. So I changed it out and now the engine runs better.

I have to keep the throttle just a tick past "fast" toward choke to get it to run at full power. But I think this is simply an adjustment on the throttle control screw.