Disco td5 doesn't like starting

Hi, I'm new as a member to this sight but been viewing for a few yrs with help on other stuff. But my td5 disco is beginning to test me now

It's got a starting issue! This is what it's had so far
Injector harness
Fpr
Injector seals (twice and genuine)
Starter motor
Air bleed valve
Battery tested
In tank pump (vdo)
Fuel lines checked with pressure gauge attached an running just over 4 bar.
Had filter housing about 18month ago

In the morning it's a pig to start an the same when I get back in it after work. Or when it's been left for over 30mins it's a pig to start. Sometimes I can run in a shop come out and it takes a few winds then. Everybody tells me get rid but I need to see this through :-/
Thanks for any help you can offer.

Common as muck.

Have you tried a search?

glow plugs but a search might help you in your answer

I did think about glow plugs but sometimes when it fires in it dies pretty much straight away. dont want to sound daft but what do you mean by search

How about a fuel problem, air in system, leaking back to tank, loosing pressure.

Once started does it run fine ?

If so - check for leaks, check for split or perished pipes, change filter, check filter housing. ????

Don't forget filter housing, sometimes they won't leak but will draw air in when stood

The owner before, a mate of mine said he had one on it 18month ago but a none genuine one. Would this part be at fault so soon.?
An yes it runs ok but a bit flat on first pull off after first start up 1800rpm then it bursts into life.

Mine would not start with less than half a tank of fuel if left a few minutes.
It was the air bleed valve in the end. Steve

Done the are bleed valve mate an tried with tank full but still no different

still sounds like injector seals, were the injector seats properly clean when they were installed

Had the seats cleaned were the injector sits with copper washer. I was talking to an engineer the other day an he said that aluminium goes hard an it creating a good enough seal so try cutting the seats to take a fine layer of aluminium off, wot do you think??

I have herd of some people having to do there's a few times before it's cured, but also I know a man who will test an clean my injectors for a fee through the bk door of a company he works for an it'll be half of what they charge if I go through the front door so think it'll be worth having this done if I'm goin down the seal route again.

still might be worth doing the simple things and cheapest things first like new filter and or filter housing ?

sounds like fuel leak/air issue to me.

i'd go over the entire fuel system to make sure it's ok.

start at the tank and see if there are any splits or leaks at the connectors, work your way along.

hows the pump running?

how's the fuel filter? sometimes they can allow air in.

if you get desperate you can hook up clear hose and watch for bubbles on the various sections. this will let you know where the leak is happening.

I've tried 2new filters an no different,
Sometimes you can hear the pump when the engine is running like it's still got air in the fuel an then other times you can't hear the pump running while driving. The clear pipe sounds like a good idea.
But having said that they run a pipe round the motor with a gauge to fpr and pressure was over 4bar which made them think the issue was from fpr to injectors. Would they be right thinking this?