He did most of those already....

 

if he replaced all of those there is no way he can have a FP issue - that is all of the parts - unless he has gas leaking from a line which he would see and smell

 

FP Relay $225? I think you have a typo.

 

I guess the things I would go back and re-look at again would be

1) Voltage at the pump
2) Check fuel pressure after the fuel filter ...again, if need be. If it's low there, then;
3) Check pressure before the filter. If it's easier, check at the pump too. Maybe the tank hose is failing internally.
4) I'd probably put a hose into a 5gal bucket and check 'flow' too (after/before the filter ..but for sure before the filter -- see if the pump is putting out good flow). Compare it to some online videos.

Basically work backwards to the tank/pump/regulator. You might have to bleed the air out of your tester's lines to make sure it's getting a good reading (air compresses). But you probably won't at the pressures you're testing for.

If it's still low I'd consider another regulator (not that expensive) or a replacement pump from like Delphi or Bosch. Either of those items could have been faulty out of the box. Who knows these days?? Maybe there's a way to test the pump directly?? I haven't had to do it. And of course replave filter if it tests bad. Look into the tank for any debris, especially water. Water is kind of hard to spot. Your pressures aren't too far out of whack. Still could be pressures, but rule out other possibilities as you are doing your checks. I've taken on a large "glug" of water at a gas station a couple times in my days. Under the worst circumstances it can mimic worse problems & take more than a couple containers of gas line antifreeze and several tanks of gas to work it out. It's a tricky one to sus out. So, yeah, you never know.

Another often-overlooked maintenance item is carbon/fuel build-up around the throttle blade. I've had that happen on several vehicles. Even a small amount can cause all sorts of strange idling and drivability issues. Clean with Throttle Body Cleaner ....and a solvent-safe soft small bristle-brush (like from a parts store). And make sure the back of the blade is clean. While you're at it, make sure the IAC solenoid passages are clean. That can cause idle issues.

Also quadruple-check vacuum hoses (for leaks). I would ensure vacuum is good before even re-checking fuel pressures. Because it's easier. Old Disco ....they get brittle and rot. Sometimes tricky to spot leaks. A good check is to put a 10" length of hose on an unlit propane torch and wave it around the engine compartment. Any vacuum leak will suck in propane and you'll hear the engine run smoother/faster. Then you know you've found a leak. Your rig could have a couple??? The cruise control has a long hose on on mine and it used to crack a lot ...the T often breaks too. There are a lot of vacuum hose leak-opportunities on these Disco's. I would for sure make sure your vacuum system is good.

Spark plug wires are another common source of problems on these Disco's. Read up on that, and watch a few videos. Certain ones are recommended. It might be worth pulling the plugs out and looking at each one (for color, etc). I'm just tossing alternate ideas out here... don't shoot the helper...

 

Hey ToeKnee25,
If you have everything unbuttoned consider adding a pressure gauge to the fuel rail. Also reseat your gas cap. This helped me with some similar concerns. I posted this in 2018

https://landroverforums.com/forum/di...ressure-90312/