ZD21 Loses Power

[farmerandy741]

My ZD21 loses power when mowing. It is not a function of the grass thickness. The symptoms are that the RPMs will decrease to around idle as if it's starving to for fuel. The solution is to disengage the mower deck whereupon RPMs will return to normal. Reengage the blades and continue for 50 yards and repeat. I replaced all 3 fuel filters and no change. Could it be fuel line leak ingesting air?

 

[Dustyx2]

The first thing I would try is loosening the fuel cap. If that helps your vent hole in the cap is plugged. The second would be to make sure the mower deck turns freely. Check the oil in the gearbox. The gearbox or spindle bearings may be failing.

 

[farmerandy741]

The first thing I would try is loosening the fuel cap. If that helps your vent hole in the cap is plugged. The second would be to make sure the mower deck turns freely. Check the oil in the gearbox. The gearbox or spindle bearings may be failing.

I ran it today in 60F weather for about an hour and it worked fine. Weird.

 

[Captain13]

Have you changed the fuel filter lately. My ZD21 did that last year and finally reached a point where it wouldn’t mow. I was in the middle of mowing the yard when it started. I shut it down, checked everything and it started right up and did fine for about 15 minutes and started bogging down again. Turned out to be the filter.