you don't need a manual to check the lines and filters, which is definitely where your problem is. follow the lines from the tank--you should have 2 filters for diesel. one will be on the engine, mounted near the injection pump and the other will be under the bus mounted on the frame rail most likely and it is the filter/water separator.
id start by replacing both, then see where that gets you. it's the cheapest and easiest thing to do. every diesel owner should know how to replace their fuel filters. our engines are very sensitive to their condition and you describe a tell-tale sign of a clogged filter.
Patina enthusiast and professional busman