Kubota KX41 revs dropping when hydraulics are activated

   / Kubota KX41 revs dropping when hydraulics are activated #51  
I agree (somewhat) but is it not working because it's faulty or because it's maxed out trying to compensate for an unusual hydraulic load?
I have had the governor out and while it is a bit worn, nothing is broken or missing and everything moves smoothly and freely - forks/fingers, flyweight, slider, etc.

I don't think this video really tells you anything. It just shows the injection cam rotating, but we already know that because the engine is running. I think you will need to get the manual for the injection pump and see how the governor works.
 
   / Kubota KX41 revs dropping when hydraulics are activated #52  
U can get a kubota engine manual and it shows all the pre-sets..
 
   / Kubota KX41 revs dropping when hydraulics are activated #53  
What strikes me is how slow that engine revs up. Something like 40 seconds or so from when he let go of the throttle until the revs stopped rising? We have the same machine, KX41 with D1105BH engine. I'm sure it doesn't take more than a second or so, maybe even less to rev up when I adjust the throttle.
I would be interested in what your RPM is at its highest throttle position? I still think someone tried to turn the power up on the OPs machine and did not understand what they were doing.
 
   / Kubota KX41 revs dropping when hydraulics are activated #54  
The max fuel screw has another screw adjuster in it..
it’s the torque screw..
When u turn one up, (add more fuel) to which u actually BACK OUT the screw, u should only turn the whole assembly..
That way u turn the fuel proportionally.. fuel goes up, torque goes up ..
It would make sense that ur correct.. On A LOT of systems, the max adjuster gets turned IN..
 
   / Kubota KX41 revs dropping when hydraulics are activated #55  
U can get a kubota engine manual and it shows all the pre-sets..
Online as well at Kubotabooks.net. Had my dealer crank both of mine up a few years ago. One is making 93 pto, the other is at 91. Hard to match them perfectly. No impact in gallons per hour used either. M9's are supposed to be factory set at 83-85.
 
   / Kubota KX41 revs dropping when hydraulics are activated #56  
Here's mine for comparison, just opening and closing throttle. A bit "boomy" at idle because the engine cover is up. Rev counter doesn't work but hopefully the engine noise is enough to make the point.

 
   / Kubota KX41 revs dropping when hydraulics are activated
  • Thread Starter
#57  
Here's mine for comparison, just opening and closing throttle. A bit "boomy" at idle because the engine cover is up. Rev counter doesn't work but hopefully the engine noise is enough to make the point.

Thanks heaps for that. Yes that is a vast difference.
 
   / Kubota KX41 revs dropping when hydraulics are activated
  • Thread Starter
#58  
I don’t think the pump has been apart and put back together by a “qualified” inj pump tech.??
He also has the max fuel and torque screw completely out.. there’s no starting point..
It’s my “guess” is, that between the rpm’s and max fuel, he’s overcoming the gov springs with any load applied..
It’s just a guess mind you..
The IP has now been professionally rebuilt and recalibrated by our local Bosch injector/pump specialist.
No change to symptoms.
 
   / Kubota KX41 revs dropping when hydraulics are activated
  • Thread Starter
#59  
UPDATE

My apologies to all for the delay. It has taken me forever to get hold of a Diesel Compression Tester with the adapters i needed.

So to update:
INJECTOR PUMP > I got the Injector Pump professionally rebuilt and calibrated by our local Bosch injector/pump specialist - no change to over revving, lack of power and bogging under load.

COMPRESSION TEST >
The manual says compression should be 412-469 PSI (Rebuild under 327 PSI)
My results:
Cylinder 1 - 380PSI
Cylinder 2 - 410PSI
Cylinder 3 - 320PSI

So all are below operating range and one below rebuild indicator.

Is low compression also going to cause the slow RPM response to throttle movement?
Or are there still other issues (eg governor) that I'm dealing with for that?
 
   / Kubota KX41 revs dropping when hydraulics are activated #60  
UPDATE

My apologies to all for the delay. It has taken me forever to get hold of a Diesel Compression Tester with the adapters i needed.

So to update:
INJECTOR PUMP > I got the Injector Pump professionally rebuilt and calibrated by our local Bosch injector/pump specialist - no change to over revving, lack of power and bogging under load.

COMPRESSION TEST >
The manual says compression should be 412-469 PSI (Rebuild under 327 PSI)
My results:
Cylinder 1 - 380PSI
Cylinder 2 - 410PSI
Cylinder 3 - 320PSI

So all are below operating range and one below rebuild indicator.

Is low compression also going to cause the slow RPM response to throttle movement?
Or are there still other issues (eg governor) that I'm dealing with for that?
I do not see how low compression could cause the slow throttle response or the high RPM. It would possibly explain a slight loss in power with those numbers but should still be usable.

I would still think governor or the fuel torque still out of adjustment. If it were my unit I would set the RPM to 1500 to 1800 and work it. Even if you did the rebuild I think this problem would still exist.
 
 
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