While looking for the torque specifications of the fuel injection pump, I saw this thread. If your Farmtrac fuel injection pump has its own oil supply, there are a couple ways that diesel fuel can start replacing the oil in the reservoir.
The first way is after some wear between the Helix element and the sleeve a path from fuel can make its way into the oil compartment.
The second possible way fuel can be found in the self contained oil reservoir is when there is wear between the pump plunger and the Fuel Feed Pump Assembly housing.
The suggestions within this thread are very helpful. When you fill the oil compartment and let it extrude the fuel out of the compartment via the overflow tube. Diesel fuel is "lighter" than oil and its "floating" above the filling oil can "replace" the fuel with oil once again. The best thing to do at this point is to check it often and see how fast the leak may be.
I found this excellent video which shows how to diagnose possible leaks. It is not in English, but the video shows specific infomation that might be helpful. The only difference I was was that they leak test in water vs in oil. I imagine that is because fresh water is much cheaper than new oil.
If the link to the youtube video does not work, then search for the title:
Tractor fuel pump leakage ! Inline pump overflow ! Element leakge test
Even with the misspellings you should be able to find it.
Hope this helps.
