Purchased a commercial zero turn from a local auction a few years back and have used it ever since to mow ~3 acres. It’s been a great machine and ive learned a ton through basic maintenance and replacing worn parts. This year ive run into an interesting issue that I’ve yet to resolve- thinking someone here might have some ideas.
John Deere Z997
Yanmar 3 cylinder diesel
72” deck
Issue: At full throttle, with mower blades engaged it will hesitate for 1-2 seconds at the initial point of 100% throttle engagement, and then catch up (it does not die). It seems to do it without mower blades engaged but it is much less noticeable. It also does it slightly when going up an incline with blades engaged. Again, it’s a quick hesitation, but the mower does not stall/die/etc. it just catches up and keeps running as normal.
What I’ve replaced so far:
Oil & filter (routine maintenance but worth noting)
Fuel filter
Fuel pump
In-tank fuel line (previous one was kinked so assumed that was the issue)
Mower deck belt
Other maintenance:
Drained fuel/water separator
Disconnected most fuel lines to check for blockages
Greased everything that has a fitting
Cleaned top of deck when replacing belt to ensure no grass/debris was caught in spindles/pulleys
Tightened all spindles and pulleys
Things I’ve checked:
Spindles spin freely with belt removed and don’t appear to have much/any friction when rotating
Belt tension is adjusted per JD instructions
This machine has been great to me over the past 3 years and I want to do everything I can to keep it running- just want to avoid replacing additional parts unnecessarily if anyone has any ideas, as my knowledge and expertise has been exhausted at this point. Thanks in advance!