Hi all. I'm trying to figure out if my low pressure side is supplying sufficient amount of fuel. From what I've read through the searches, it is possible to tap a pressure gauge on the fuel filter but I'm not sure which part of the fuel filter I should be getting the low pressure read. This is because my fuel pressure on the high pressure rails tends to fluctuate up/down quite a bit when on load but it stays stable when I'm cruising. I've done pretty much everything on the high pressure side. I'm just wondering if the low pressure side could be clogged at the in-tank pump strainer. As in if it is supplying enough fuel to run the vehicle but struggles when on load hence the HPFP ends up overworking when pressure is in demand. I'm also getting a faint whinning noise at the hpfp. It's just a theory at this point. Please advise if it is normal to see in-tank pump or the lift pump to fail at 70k miles? I'm deciding if I should just replace these if the pressure is indeed lower than 5 bar after the lift pump. Or clean up the strainer and try first. Trying to minimise the risk of spilling diesel all over the interior.

Appreciate if anyone can advise which part of the fuel filter housing I can tap to get a gopd low pressure read.