Have you done the Hutch and Harpoon mod with a Racor PS120 pre-pump filter for about $80-100? It removes the in-tank screens and replaces them with the PS120 along with removing air in the system which can be caused by a number of things.

Next could be the fuel pump at that mileage if it has never been changed or is clogged.

 

 

I would be willing to bet it's just a very tired fuel pump. Could also be partially plugged screens inside the tank, though, or even a combination of screens and pump. I'd do the H&H and install the PS120 at the same time, and if you do that, plan on replacing the plastic pickup foot in the tank as well. Then, if you still have fuel pressure issues, replace the pump. Better yet, go ahead and replace the pump at the same time anyway because it's past time to do so.

 

 

Hutch Mod: Riffraff Diesel Hutch In-Tank Fuel Mod Kit - Riffraff Diesel Performance

Fuel Pressure Regulator Spring Kit: Upgraded Fuel FPR Spring Kit 99-03 - Riffraff Diesel Performance

Racor: Racor PS120-01 FUEL FILTER ASSY. PRE-SCREEN
This is where I ordered the last three from. They generally ship the same business day or the next if it is late in the day. This serves as a pre-pump filter and eliminates the need for the in-tank screens.

You don't have to purchase the pump from here; however, this is the pump you want if you want the stock pump which most of us will recommend. Anything other than a stock pump is generally a waste of money unless you are shooting for 450-500+ HP.

Fuel Pump: Bosch OEM Replacement Electric Fuel Pump (F81Z-9C407-AC) OR

There are existing threads on the additional parts that you will need for the Hutch Mod. The Harpoon Mod does not require any additional parts for installation. You will need a PVC cutter however.

 

 

IIRC it does not come with the barbs so you add a 3/8" barb that is threaded for 1/2"....if that makes any sense...I don't know how else to explain it so here is a link: https://www.ebarnett.com/Sku/261067/proplus-brass-hose-barb-adapter-12-in-barb-x-38-in-mip-lead-free-076335185361?cid=Shop_bing_barnett_all_261067&CID= Shop_bing_barnett_all&msclkid=3bee2312a6c318758814 79dfc687ecb5&utm_source=bing&utm_medium=cpc&utm_ca mpaign=CPCS%20-%20UF%20-%20Shopping%20-%20Desktop%2FTablet&utm_term=4579946967247263&utm_ content=All%20Products

Holy link address length Batman....I can't get the add a link function to work.

 

 

A fuel pressure regulator prevents pressure from going too high and nothing else. I say don't waste your time with the fuel pressure regulator, since the pressure doesn't go over 65 PSI.

Bad O-ring seal on the quick-disconnect to the fuel tank, clogged screens in the tank, debris in the fuel pump intake, plugged fuel filter - these are all common causes of low fuel pressure. After analyzing the fuel pickup between the pump and the tank, and doing the Hutch mod myself - I say every stock truck out there needs the Hutch mod (with a Racor pump pre-strainer) to make up for the engineering faux pas.

Does the fuel pressure improve with a full tank?

 

Great catch, Rich! He might just be leaking into the "straw" at a lower tank level.

 

 

 

report back when you find the problem. That tank will be heavy now that's it's full!

 

Drive far or get a bunch of fuel cans. You want that thing EMMMPTEE when you drop it.