I am not a mechanic so just a few thoughts that might be of assistance. First, from the Ford 3.0 Coffee Table book I read that the low pressure fuel pump is in the tank and must produce at least 51 psi or you will get the code and warning. The problem is that the high pressure pump must have adequate flow and pressure or it can be damaged, and that is an expensive repair. There is a thread here somewhere on that issue, I will see if I can find it.
Causes for this code may include: Dirty fuel Plugged fuel filter Restricted fuel line (e.g. kinked, clogged, etc.) Fuel pump pickup dirty Unstable fuel Fuel injector defective Weak low pressure fuel pump Sludgy fuel (e.g. old, thick, contaminated)
Here are some screen shots from the Coffee Table Book:
Based on this, I would think it necessary to verify the system is getting 51 psi at all times.
Edited to add: Here is a link to our discussion on the high pressure pump. Adequate fuel supply is a big part of it's longevity: CP4 Failure
So, you could be looking a failure of the low pressure pump, sensor issues, filter issues, electrical issues or whatever. A quick check of both filters for any seepage or leaks would be a first start. I am guessing a diesel tech might put a gauge in line of the fuel after the second filter to verify minimum pressure. Wish I had a quick fix for you. By the way, the Coffee Table Book says once the switch triggers it is supposed to give you the warning, set the code and then derate engine power. You didn't mention the engine derating.
Causes for this code may include: Dirty fuel Plugged fuel filter Restricted fuel line (e.g. kinked, clogged, etc.) Fuel pump pickup dirty Unstable fuel Fuel injector defective Weak low pressure fuel pump Sludgy fuel (e.g. old, thick, contaminated)
Here are some screen shots from the Coffee Table Book:
Based on this, I would think it necessary to verify the system is getting 51 psi at all times.
Edited to add: Here is a link to our discussion on the high pressure pump. Adequate fuel supply is a big part of it's longevity: CP4 Failure
So, you could be looking a failure of the low pressure pump, sensor issues, filter issues, electrical issues or whatever. A quick check of both filters for any seepage or leaks would be a first start. I am guessing a diesel tech might put a gauge in line of the fuel after the second filter to verify minimum pressure. Wish I had a quick fix for you. By the way, the Coffee Table Book says once the switch triggers it is supposed to give you the warning, set the code and then derate engine power. You didn't mention the engine derating.