Toro Wheelhorse sputters under load

[jpilk99]

I have a Toro Wheelhorse that sat for a year and I’m trying to bring it back to life. Drained the old gas, got a new fuel filter, out on a new carb …and it starts right up and drives around in flat surfaces. But the minute I go up a hill or engage the mower deck, it sputters …assuredly because it’s not getting proper amount of fuel? Carb only appears to have one air/fuel screw and I’ve turned it out and in but no change.

 

[ultrarunner]

I've had some success adding seafoam to small engine fuel tanks correcting problems...

Picked up a like new mower that sat 4 years?

Ended up picking up a cheap replacement carb online because I wasn't able to cure whatever it was by taking apart and cleaning the carb.

I'm guessing fuel flow is good and the condition happens with and without the fuel cap in place in the case of a obstructed cap vent?

Weak spark can run fine until under load too.

 

[masseyrider]

Drain the gas. Put in some premium. I run premium all the time in smaller engines. Better for the engine and it takes longer to go bad if you don't use the machine often.
Put some good quality carb cleaner in and let it run for 15-30 minutes.
Your carb jet may have some residue from standing too long with the old gas and if things go well the carb cleaner may clean it out.
Sometimes works...

 

[Eagle1]

Check your governor... linkage and base settings. That is what keeps the RPM up when a load is applied.

 

[Gee Ray]

Put a fresh spark plug in it. If that doesn’t correct it, take the shield off the covers the magnet and take Emery cloth (sandpaper ) and clean the surface of the magnet.

 

[oldnslo]

Can you operate the choke when it starts cutting out to see if enriching the fuel mixture helps.

Does it idle smoothly?

If turning air mix screw made no difference that points towards a plugged fuel passage which is probably part of idle circuit.

 

[RandyT]

If running normal at idle but struggles under load I would be cleaning the carb, paying special attention to the main or high speed jet. Could involve part of the idle circuit, but either way needs a good carb cleaning.

 

[masseyrider]

If running normal at idle but struggles under load I would be cleaning the carb, paying special attention to the main or high speed jet. Could involve part of the idle circuit, but either way needs a good carb cleaning.

like I like to do, start out easy and work your way up the difficulty scale.
All fresh fuel and rich on the carb cleaner solution.
Run it for half hour at higher (not too high) idle so everything gets good and warmed up.
Sometimes that's enough without having to dismantle anything.

 

[jpilk99]

THANK YOU ALL!!!

Here's some notes:

I did drain the tank, blew out everything, installed new lines and new fuel filter.
Always use premium gas
Put in new spark plug
Put in new carb, though likely not 100% OEM match; $35 on Amazon - which I've had very good success with many other carbs
Did not put in Seafoam given everything above

Interesting that today, after reading some comments about applying choke while machine started sputtering, I was shocked to see that the engine basically cut out - stalled. I immediately pulled the choke off and it went back to standard running; which is sputtering under load. When on flat ground or going down hill, full throttle, it does ...great. Coming up hill or with PTO engaged, it sputters.

ODDLY, after mucking with the choke, I noticed that the sputtering faded away on lower throttle. I actually mowed the lawn a bit at maybe 70% throttle. As soon as I put the throttle higher it sputtered. And if I put it all the way up to choke, it just stops running.

Here's a video I just took:

 

[Richard001]

Check the oil level sensor. If the machine works on level ground and only has issues when on a hill, it's not a fuel issue.