Husqvarna zero turn dies when blades engaged (or rrandomly while mowing)

[davelobi]

I have a Z4217 Husqvarna with the 17.5 hp Briggs Intek.
It is cutting out (dying) quite often while mowing.
If I keep cutting when it starts dying it will shut right down.
If I stop it will usually catch back up and keep running.
Usually, if I disengage the blades it will stay running and dies more if blades are left running.
I can't quite tell if it is cutting out electrically or fuel related but it seems electrical to me.
I have removed and cleaned the carb but didn't find anything suspect there. Fuel filter flows freely. Gas cap is vented and free.

Is there common things I can look for? I wonder about the multitude of electrical connections with the many safety switches everywhere.

Thanks in advance for your wisdom or ideas.

 

[Fish]

Does it have the little electrical solenoid on the bottom of the carb?

 

[davelobi]

yep. solinoid on the bottom of the carb.
It moved freely when I had carb apart, not sticky at least.
does it go bad?

 

[Fish]

Well it can go bad, but a voltage drop can make it shut off the fuel, i.e. a drop in voltage from a low voltage regulator output and a high draw
of voltage from the electric pto. One easy way to isolate it is to run a temporary jumper wire from the battery to the solenoid, then mow, and see
if it still shuts down.

 

[davelobi]

Well, I bypassed the solinoid on the bottom of the carb with a hot wire from the battery. I could hear the click as it opened and shut.
After re-start I started mowing, all happy...for a lap and a half. It seems to get worse as the engine gets warm.

What would cause problems with the motor warm/hot (up to temp) ?

Like before, when it cut out, if I stopped and let it catch back up, I could keep mowing. The distance I can go before it starts cutting out again gets shorter and shorter each time. It runs beautiful cold and at first. I have to think it is heat related.

any ideas?

 

[Fish]

When the engine is cold tomorrow, you need to pull the valve cover and check your valve clearance.

 

[davelobi]

When the engine is cold tomorrow, you need to pull the valve cover and check your valve clearance.

Ohh, not what I wanted to hear, lol.

Any chance you happen to know the specs on the valve clearance? 17.5hp Intek Briggs

I'm leaning towards possibly coil? Maybe? It sure looks like crap. seperated, rusty, been stored outside. Heat increases resistance right? This seems heat related. I understand the possibility of a valve being left open if hot enough to grow in length but it starts right back up nicely.

 

[Fish]

Briggs and Stratton Valve Clearances

 

[taxidermist]

I had NGk spark plug go bad and it did this same problem. It would run all day with no load. When it would get hot the plug would start shorting out and lose power. With a big twin one cylinder will carry the other until a load is applied.


Its worth a shot.

Rob

 

[davelobi]

Well, I tried jumpoer wire to the carb solinoid, no different.
Fuel filter fine, gas cap vent fine. Pulled and cleaned carb, no different.
Lasahed the valves this morning, no different. (were a little on the big side, rather than too tight)
Replaced the coil this morning, no different. .. for a while.
It seems to cut out under a load when hot. Runs fine at first.

My grass is getting too long so I have my kid mowing anyway, stopping and letting it catch up when it starts to stall.
Now it seems to be doing fine after a half hour of mowing. Full speed, full throttle, hot engine.

I still may replace the spark plug.

What could have possibly changed by its self that it is mowing now? I mean, the last thing I did was to replace the coil but it still acted up for a while after that but may be ok now. I'm not convinced it is fixed but she is still mowing at the moment.

any other ideas?