z930m EFI loses power after 20 minutes

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FisherCat930

Forum Newbie
I have a 2014 z930m EFI that starts to run a bit rough and loses about 50% after mowing for 20-30 minutes. The check engine light does eventually come on, but the code seems non-sensical. Once I turn off the PTO the engine revs back up to normal.

I have replaced coils, fuel filter, checked fuel lines, new spark plugs, and had it at my local JD dealer twice now to no avail.

I've pulled each plug out to see if I could narrow it down to one cylinder, but neither one seems to make a major difference.
Any suggestions?
 
Possibly EFI high pressure pump not maintaining proper pressure after it gets hot. Would have to have a fuel pressure gauge on the system at time of failure to prove it.
 
It is not the mower that is running bad but the engine did I miss something where you posted the kind of engine and model no. I know JD is a SSO and you have to go back through them for parts. But an engine is an engine and may have the same symptoms as other engines of this type on other mowers. Anymore you have to have the soft ware and the different ways to hook it up to a computer to diagnose the problem.
 
FisherCat930 said:
Looks like there are two fuel pumps on this model? Are you talking about #5 or #10 on the diagram below?
I have actually replaced #10 a little while back thinking it might be the culprit.
z930m EFI Diagram
Click to expand...
#5 which is the EFI fuel pump. That pump is electric and there have been cases where the pump will go goofy and cause low pressure after running for awhile. Will need to be connected to a fuel pressure test kit and see if the pressure drops below normal when then engine acts up. Also if you know what P-code was that would also help.
 
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