John Deere 4040 RPMs fluctuate any ideas?

[kck]

I have a JD 4040 in good overall condition, but when under a PTO load it will not maintain optimal RPMs. I changed the air filters, but that didn't help. We are pulling a hay cutter and 15ft mower in light conditions. Any suggestions?

 

[Hoeman00]

Change the fuel filters first then if it doesn't improve it may need the injector pump rebuilt.

 

[kck]

Thanks for the info. I will try changing the fuel filters and see if that helps.

 

[art]

Make sure that you have a good flow when changing the filter. For the age of the tractor you might have some stuff in the tank clogging the outlet. Otherwise it would be back to the pump.