Hi Richard,
sounds like the plungers and sleeves are dry and some loose juice should help lubricate them--make sure it is a clean fluid and not decanted stuff as the fine dust settling in there could be the issue or moist ambient air could start corrosion too.
It should be remembered that these units have the injection pumps running in diesel fuel and this lubricates them and helps prevent corrosion issues when water free fuel is used.

From memory I believe we were told that Japanese engineers came up with this Sleeve Metering design that worked well with their fuels of the day but I suspect was less so else where.
Cat would say they addressed the issue by re-fitting a later version of the previous Compact pumps which they called Interim Scroll this then led to the next generation of Injection Pumps which  they called New Scroll.
Cheers,
Eddie B.

Those pumps are really sensitive to any water in the fuel or moisture. Rust is probably the biggest culprit contributing to sleeve metering problems.

thanks for the replies on this.....will have to get back again to the tractor soon

Out of interest would anyone have for sale the engine barring tool and the timing pin for this engine? I looked on ebay and its all ex-ChyyNa stuff.

Hi Richard,
for a timing pin in a pinch you can use a suitable neat fitting sized drill bit installed with the solid chuck end down the timing hole, a piece of drill steel or stainless rod of the correct size will work too.
From the Factory the sleeve metering Injection Pump timing pin should be stored/screwed into the Torque Spring group cover at the bottom right corner--1/2" or 9/16" bolt head from memory. You need to remove the Torque Spring cover to get the timing bolt/pin down deep enough to engage with the Inj. Pump camshaft timing slot.
See scan below for bleeding air from these pumps or you will have lots of cranking to get the fuel level up in the pump body to reach the injection pump elements every time you go to start it even after it has run for some or many times.

Scan below shows how to bleed these inline pumps.

Cheers,
Eddie B.

Thanks Eddie,

I had that diagram with me on the last visit, remembering that there was a bleed screw somewhere.......it did let out some air, but basically it seems the rack is sticking either on the plungers or further back the pump.....inclined to think that there's a bit of corrosion somewhere along the line and half expect to have to remove it and get the thing serviced.

The annoying thing is that it actually drove in to the spot in the workshop, only after removing the governer box (in the spring of the year) has this problem occurred