I am speaking in generalities here, based on marine diesels, but it may apply.

All the diesels that I have worked on have two fuel pumps, a low pressure pump and a high pressure pump. The low pressure draws the fuel from the tank to the engine and the high pressure forces it through the injectors. Older injectors may need bleeding. Very analogous to bleeding brakes - you have to get all the air out. On the diesels with which I am familar, you crack the nut securing the injector and pump fuel until it flows around the injector. A lot of pumps have a manual wobble handle on the pump for this purpose.

If the fuel has been sitting for a while it may, as strange as it sounds, have algae in the diesel. The algae will clog your filters and your injectors. You can buy an algacide at any marine store. If your Scout has the serviceable type fuel filters, I would pull them and clean them. If not I would replace the fuel filters.

Finally, your starter electrical circuit needs to be up to snuff. It takes a lot of pressure to combust the diesel and a weak battery will lead to a lot of frustration.