2.5DSE fuel problem

Recently went through a 'difficult starting' phase, 30-40 seconds continuous cranking fefore starting from cold, once started it was perfect all day, then same again next morning ( 0600).
Since I fitted new glow plugs last year, I thought I'd try the glow-plug heater relay, no dice, bought & fitted 6 new glow plugs & viola!! tested the 'old' ones only to find that 3 were dud.
That was last week, then a couple of days ago I noticed that it seemed WELL down on power (torque) so I changed the fuel-filter, IMMIDIATELY there was loads of air-bubbles in the clear fuel line, I thought i'd fitted the filter badly, but no, so I completely removed the filter, placed a container under the filter housing & switched on, nothing at all, not a drop of fuel from the housing, filter back on( filled with fuel first), & it takes about 20 seconds of cranking to get it going, & again, loads of air bubbles.
I assume that the injector-pump must somehow be 'pulling' the fuel from the tank, just enough to keep the engine running, but without the tank-pump running, its a bit hit & miss!!
Should there be fuel discharging from the filter-housing upon switching on? or have I got it wrong, IF the tank-pump is shot, is it much of a job??

Hello. Yes there should be fuel pumping out of the filter when you disconnect the fuel out pipe but only for the first 10 seconds or so of ignition turn on. Does it start ok after the first start of the day if so I would check the fuel leak off pipes between the injectors as these can become perished and let the fuel run back to the tank and let air into the system. Hope this helps

No fuel from the filter housing at all, & it takes a long time to start again, even a few mins after shutdown, all leak-off pipes are dry & appear ok.
So I guess the injector-pump is having to 'drag' the fuel from the tank all by itself!

Is there a fuse controlling the pump??

even though the leak off pipes are dry they may still have cracks in them and be allowing air in, I would change them anyway as it's all of a fivers worth of tubing from your local independant LR garage. IMHO it sounds like the fuel pump may be duff but worth checking that it's getting power to it first though!

Well, as usual, at about 0200 I suddenly thought, 'what if the pumps not getting voltage'?
So after a quick gander at the handbook, I discovered that fuse 39 in the engine bay is the fuel pump supply, & lo, it was 'popped'!!
Replaced it & VIOLA!! shes running like her old self, whats worrying me now however, is what made it 'pop'!!
I'll run it for a while & see what happens, its possible I suppose that a fault in the pump may well still be the cause, time will tell.
Happy (for the moment)