Zero Turn power

[Williy]

My question is just because the spark plug is new
don't mean its good as I have gotten bad plugs.
Also check your coil contacts and the flywheel
contact to see if they are rusty and need a cleaning.
Did you check the bowl on the carb again? If could
have gotten a small piece of dirt in it again.

willy

 

[redneck1952]

Has it always been low on power, or just happened?

I received it used and it had low power but replacing the fuel pump and carburetor cured that. this just recently it started losing power again. The carburetor has been cleaned and there is sufficient fuel supply to it.

 

[redneck1952]

My question is just because the spark plug is new
don't mean its good as I have gotten bad plugs.
Also check your coil contacts and the flywheel
contact to see if they are rusty and need a cleaning.
Did you check the bowl on the carb again? If could
have gotten a small piece of dirt in it again.

willy

I removed the carburetor and cleaned it to make sure. As for the plugs I agree that new doesn't mean good on any part. That's why I have purchased some more

 

[PuffyC]

If you pulled the belt and the deck moves fine then at least you know it's an engine problem. Some things I didn't see mentioned:

- Are you sure the throttle linkage is fully opening the carb when at full throttle? If not that would describe what you're seeing.
- Are you sure the choke is fully disengaging when off?
- Could be a vacuum leak somewhere. Might try the WD-40 trick to see if the RPM changes when you spray around hoses and gaskets.
- Could be a bad alternator/regulator, but then your battery would likely eventually die as well. Might be worth checking just to make sure you're seeing over 13v when running and getting a hot spark.
- Are you sure the air filter an intake are clear? Might try pulling it all off just as a test.

If none of that turns up anything I'd do a compression check just to make sure it's right. Since you bought it used there's no telling what kind of shape the internals are in. Maybe you changed the oil and whatever goo the seller put in as a bandaid got dumped, or maybe it was marginal and the original owner was running some high viscosity oil to mask the problem, etc. Not likely but worth a shot if nothing else pans out.

 

[Tinhack]

I've got a 2021 26hp ZT with a 60" deck. It says to engage the blades at power. That took some getting used to mentally. The thing doesn't know it's in high grass/weeds. It mows down everything. My old 18hp 52" ZT didn't like blade engagement at power. You had to engage the blades just off idle then throttle up but always cut great. It was a 1986 model. The difference was the old mower had a U-joint PTO shaft ahead of the blade belts.

I'm just throwing something else out there to check when all else fails. That is the possibility the flywheel key is partially sheered from hitting a stump or large rock. It may be slightly hard starting, maybe not. Depends on how far the flywheel turned. But even the slightest amount of sheer will rob the engine of horsepower at high end. Good spark, good gas and clean air should provide a one-second crank to start the engine. It shouldn't have any problem reaching cutting speed. If it doesn't, check the flywheel.

 

[Fuddy1952]

I received it used and it had low power but replacing the fuel pump and carburetor cured that. this just recently it started losing power again. The carburetor has been cleaned and there is sufficient fuel supply to it.

Drop back and punt?
To me if it was low on power, you replaced fuel pump and carb which fixed it...now if it's doing exactly the same thing behaving the same exact way...I'd be thinking about the fuel pump and carburetor. Regardless if you took it apart, getting fuel, etc.
First though I'd remove gas tank cleaning it well.

 

[5030]

NO Tach, never have seen one on a mower.
Don't have tach to use on a mower either. Have to find one.

Mine does, came with not only a tach, but a maintenance interval reminder as well. So does my wife's zero turn, we have 2. Both Cub Cadet's, both with Hydro-Gear transmissions.

 

[5030]

We always engage the blades, just above idle and then bring the motors to cutting speed (3600 rpm).

Much easier on the electric pto clutch and the belt drive. Remember, the electric PTO clutch is very similar to the AC clutch in your car, that is, it has flat friction discs that engage each other so a lower engagement rpm = less friction pad wear and the clutches are expensive to replace.

 

[Bearsixty7]

We always engage the blades, just above idle and then bring the motors to cutting speed (3600 rpm).

Much easier on the electric pto clutch and the belt drive. Remember, the electric PTO clutch is very similar to the AC clutch in your car, that is, it has flat friction discs that engage each other so a lower engagement rpm = less friction pad wear and the clutches are expensive to replace.

I agree and that's how I have done mine even though the manual states to engage at 3000rpm. I figured it had to be a typo and was probably meant to be 2000rpm.
Lots of people on the Spartan FB page say "Engage at 3000, it has a soft start clutch" I just have to laugh to myself.

 

[tomplum]

I didn't see where you said what engine you have. I did see that coils have come up a couple of times. When you drop a coil and that cylinder isn't running, the engine gets anemic feeling and power greatly suffers. I've also seen the choke come up. If this is a Kohler with their smart choke they do fail, the plate closes when it isn't supposed to.