Just to correct a wrong statement - pressure does matter in this situation. Any material vaporizes if the temperature and pressure are at the right conditions - if diesel is warm(>100F) and under a certain amount of vaccuum, it will vaporize (called cavitation) - not good for any pump.
I AM NOT SAYING THAT USE OF A PRIMELOC IS CAUSING THIS TO HAPPEN, BUT THAT THE STATEMENT THAT PRESSURE DOES NOT MATTER IS INCORRECT. Having said that, day-in and day-out I deal with fluid flows ranging in the Millions of Gallons per Day - I understand fluid flow, and I would not install anything in my fuel system that would cause anymore restriction than the stock filter (which really is pretty low).
Also remember that the outlet pressure of the filter (stock or otherwise) is not the same as the injection pump inlet pressure - there will be more pressure loss in the line from the filter to the injection pump (just like from the discharge of the lift pump to the filter).
I AM NOT SAYING THAT USE OF A PRIMELOC IS CAUSING THIS TO HAPPEN, BUT THAT THE STATEMENT THAT PRESSURE DOES NOT MATTER IS INCORRECT. Having said that, day-in and day-out I deal with fluid flows ranging in the Millions of Gallons per Day - I understand fluid flow, and I would not install anything in my fuel system that would cause anymore restriction than the stock filter (which really is pretty low).
Also remember that the outlet pressure of the filter (stock or otherwise) is not the same as the injection pump inlet pressure - there will be more pressure loss in the line from the filter to the injection pump (just like from the discharge of the lift pump to the filter).