Tractor slowing while mowing grass

[rbargeron]

I use my my L5450 with 90" finish mower to cut about 10 acres of gently-sloped field grass around my place. I run it at about 1800 rpm on the 750 pto speed. The engine (49 hp) has always had way more power than needed.

But a couple seasons back it developed a symptom where after a couple hours it will starts losing rpm, about 200 rpm (to 1600 or sometimes lower). I just kept going and didn't mind going a bit slower. Other tasks like snow blowing don't show the slow-down.

The main 7-acre grass parcel is sloped around 15 feet in its length of 400-500 ft. The fuel starvation thing is more noticeable when headed up-slope. If clutched, it recovers and then will resume normal rpm . At the end of a row, turning up-slope can bring the rpm drop too.

I've tried several things - most recently with new fuel in a new can atop the hood (eliminating the tank & filter) - no change.

I've never tinkered with the governor springs at the diesel pump. Anybody had experience? Other ideas?

Take care, Dick B

 

[armylifer]

Since you mentioned that it only happens while mowing, I would be looking at the mower to see if there is a pulley wearing out or if something is wrapped around one of the blade shafts. Sometime bailing twine or fence wire can get wrapped around one of the blade shafts and cause the mower to drag on the engine and slow you down.

 

[85Hokie]

Dick,

I am confused - you mention 1800 rpms on the 750 PTO speed......

now this might be wrong - but



I would think you would want to cut at 540 at a higher torque curve - thus 2300?

 

[North Idaho Wolfman]

No springs or adjustments to the governor are needed or allowed.

Are you getting any smoke when it slows down?
If you are then the next thing to do is add Cetane boost to the fuel, like Stanadyne.
If you get an improvement, your more than likely do to have the injectors replaced.
Being you have pencil injectors they are rarely rebuildable.
Call Oregon Fuel Injection and ask them if they can rebuild them.

 

[rbargeron]

It seemed to me that if the injectors were changing through-put during use, they wouldn't change performance by simply reducing the fuel flow and then speeding it up again? Maybe I'm not understanding the point you are making?

 

[SDT]

I use my my L5450 with 90" finish mower to cut about 10 acres of gently-sloped field grass around my place. I run it at about 1800 rpm on the 750 pto speed. The engine (49 hp) has always had way more power than needed.

But a couple seasons back it developed a symptom where after a couple hours it will starts losing rpm, about 200 rpm (to 1600 or sometimes lower). I just kept going and didn't mind going a bit slower. Other tasks like snow blowing don't show the slow-down.

The main 7-acre grass parcel is sloped around 15 feet in its length of 400-500 ft. The fuel starvation thing is more noticeable when headed up-slope. If clutched, it recovers and then will resume normal rpm . At the end of a row, turning up-slope can bring the rpm drop too.

I've tried several things - most recently with new fuel in a new can atop the hood (eliminating the tank & filter) - no change.

I've never tinkered with the governor springs at the diesel pump. Anybody had experience? Other ideas?

Take care, Dick B

Heavier grass?

Dull blades?

Mower clogged with debris interfering with clearing?

Cutting closer?

Discharging cut grass back into grass yet to be cut?

Lots of variables, not all regarding tractor.

Yes, I agree that 1,800 RPM is almost certainly too low.

 

[North Idaho Wolfman]

My point is that if there is a fuel delivery issue it could be caused by fuel injectors that are getting tired.
They can cause low or poor fuel delivery when they get old and too much heat is introduced to them.

It's just one train of thought.
If your direct feeding the injection pump fuel then you've eliminated the fuel filter housing, lines, tank, and lift pump so, your next options would be fuel injection pump, fuel injectors, valve lash or some other mechanical failure.