Diesel engine getting sufficient fuel to run at low idle but starving of fuel at higher revs or load??
Sounds like it 'might' be a blockage in the fuel supply. Typically a blocked pick-up filter in the fuel tank. (See numerous threads on here for this symptom in all brands of tractor).
Edit: See below.
And/or the main fuel filter could be blocking-up. When did you last service the machine and change your filters?
Edit: I see it's a Gravity feed to the Glass Bowl. You could verify fuel flow by dropping the bowl and checking the fine gauze mesh in the top. Fuel should flow freely into a catch-can.
Similarly down at the engine where the fuel lines feed the Injection Pump. Remove the pipe and check for flow.
Despite your not having a suction Lift Pump it still seems like a poor fuel flow to me.
EDIT AGAIN: :ashamed: I see for later serial numbers you do have 'proper' filter elements (A pair of) so you may need to supply the VIN of the machine for further assistance. Which fuel system do you have. Glass bowl or 2 x cans?
Pics too. We like pics. These are pretty cool-looking old crawlers. :thumbsup:
