help! zd331 runs rough when under a load

wingnut1623 · Dec 9, 2016

I have 2 zd331 mowers, one 60" and another 72". I just did a 500hr service on em both, and now they run rough under a load. I changed the fuel filters, of course, and checked to make sure the fuel in tanks was clean (it was).

I replaced the filters as they were on the mower, with the dowline one "upside down" to facilitate flow through the loop.

Any ideas out there? What did I do wrong??

rentthis · Dec 9, 2016

there should be 2 filters on each of those machines. Did you change both of them? The filters should have an arrow indicating direction of flow. Be sure those point in the right direction.

wingnut1623 · Dec 9, 2016

yep, used the Kubota filters, installed the way the old ones were in. I was a bit confused to see one "upside down" until I figured out that it was a twin filter loop to the injectors
I just stepped out in the shop and bled the air at the injector lines. No help, air is out of system and still same problem.
No power when under a load, especially when mower engaged. will run rough for a minute when still, then run normally until I move again. Weird.

rentthis · Dec 9, 2016

are the fuel flow arrows on the filter pointing in the right direction?

rentthis · Dec 9, 2016

If all you did to the fuel system was change the filters and they are in the right direction and tightly clamped, the only other thing I can come up with is to bleed the injectors to see if you have some air in the lines. It seems to me that they should have bled themselves it they started.

wingnut1623 · Dec 9, 2016

One of the new fuel filters was almost completely restricted. I used another (Napa) filter and the problem is resolved.

I do appreciate the help though, Rentthis

rentthis · Dec 9, 2016

Super! I use NAPA filters too. Don't tell my dealer

cviola2005 · Dec 9, 2016

Does your model have a bleeder at the fuel inlet on the injector pump? I've seen engines run rough until that it opened and bled, even if the injectors are bled.

Daren Todd · Dec 9, 2016

rentthis said:
Super! I use NAPA filters too. Don't tell my dealer

I use Baldwin

I get the in lines by the case (12) for around $14. For my light towers, $3 for the oil filter and $4 for the fuel filters versus $12 and $18 through the dealer. My deutz filters are $6 for the oil, $8 for fuel. Double that price from o'rileys and napa, triple if purchased through deutz.

My air filter that retails for $160 through o'rileys with the company discount, and deere for $200 bucks is $58 through Baldwin.

At those prices and savings, I can order by the case out of state, pay freight and still save a bunch of money.

rjcorazza · Dec 12, 2016

Glad you got it figured out. That filter setup has caused folks a lot of hassle on the ZD's and BX machines. That's the first I've read of one with a defect, but it does happen.
On my zd326 I replaced the first filter with a large 2u spin on filter.

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help! zd331 runs rough when under a load

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