Fuel pump has been mentioned and you say there is a bleeder screw on the pump. First we need to decide what injection pump you have. The first picture describes the two types of injection pumps that could be possible. I doubt that a 2000 had an inline pump from factory, but things may have been swapped during the years. If you have the inline type, stop reading here. The rest of this post regards the CAV DPA type.
First, do you have a lift/priming pump mounted between the filter head and the injection pump, or is the line from the filter head going directly to the injection pump? If there is a lift/priming pump, that can be the problem. But that is another issue.
On the CAV DPA type injector pump, there is an end plate where the fuel enters. This end plate contains a filter and a valve. Those can cause various troubles if they are not clean and in order. It could be so that the bleeding gives a flush that makes fuel flow more freely. Same for the towing that gives more pump speed than cranking with the starter. Taking it apart and service it can be the solution to your problems, and I would do it before the ordeal and costs that servicing the whole pump will be.
Taking the end plate apart includes that you will be dealing with several small parts that are spring loaded. Some say it is best done with the end plate in place on the pump, but I think you have better control over the parts if you remove the end plate from the pump and deal with it on the work bench.
First, clean the pump and surroundings properly.
Look at the diagram showing the parts in the end plate. The details may differ from what you have but it gives a hint of what you should expect.
After removing the inlet line, crack the threaded collar (#10) loose. Do not remove it. It is easier to crack it loose this way than with the end plate removed.
Unbolt the four screws that holds the end plate to the injection pump. There is an o-ring behind the end plate that needs attention.
Put the endplate on a clean workbench. With a tool (screwdriver) through the threaded collar, you hold back the parts as you unthread and lift the collar. Then, very slowly, release the pressure on the tool to relieve the spring pressure.
Remove the parts and place them in order on the bench. Clean and examine the parts.
If you are not comfortable with the operation, bring the end plate to a shop and have it serviced there instead.
At reassembly, the four screws holding the end plate to the injection pump should be torqued to 5.1 Nm (45 lbf-in).
This post was edited by Hacke on 07/28/2021 at 06:45 am.