Good work Luciemay…..!
Great that it starts ok………especially @5am…..&-5deg if it’s as cold as here……!  FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

I may have been a bit premature with this morning's post.
I came out after work (car been sat for 8 hours) and it struggled to start although when it did start it ran perfect all the way home some 15 miles.
I left it a couple of hours and now it won't start at all. I've pulled the return off the fuel filter and my hand pump struggled to pull the fuel through and there seems to be air bubbles in the line.
Any idea's guys

My thoughts ...
The fact that you have air bubbles in the line must mean that you have a leak somewhere.

The fuel is sucked up to the HP pump, so the negative pressure can entrain air if a connection has a slight leak, without any fuel leaking out. Jules

Luciemay,

I agree with Jules………
You need to check the incoming fuel pipe from the fuel tank…..connect to it if possible to see if all ok ….fuel being sucked-up………..pity pipes are solid black, if they were clear you could see any air bubbles.
If ok check output to HP pump from filter if possible……see if it’s clear or air…..

Assuming plenty of fuel in tank……! Assuming your suction pump is ok…..!

Good luck… FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

It has started again after I've primed it through the return from the filter, i can see air bubbles going up the fuel feed pipe from the filter to the HP pump and loads of bubbles coming out of the return. If if turn it off and restart a couple minutes later it turns over quite a lot before firing.
Any ideas

It has started again after I've primed it through the return from the filter, i can see air bubbles going up the fuel feed pipe from the filter to the HP pump and loads of bubbles coming out of the return. If if turn it off and restart a couple minutes later it turns over quite a lot before firing.
Any ideas

You have a leaky connection somewhere - probably one of the fuel filter connections on the neg pressure side.

Everytime you prime it - you are using positive pressure to push fuel (and bubbles) round to the fuel tank. Jules

Agree with Jules …again..
As per my post yesterday it would be good if you can make a good connection to the input feed from the fuel tank to fuel filter…..check for no air being drawn up. If air is present you could have a damaged fuel line /connection. If ok thé filter is suspect.
The problem is that fuel is sucked from the HP pump from the tank via the filter……..thé slightest leak will allow air into the fuel…..also will allow fuel to return back to the tank when the engine is stopped.
This would explain why engine has to crank for a while to draw fuel up……..thé slightest leak ( negative pressure) will cause this. Also you won’t see a leak ……
Filter seems suspect…..
Lots of other explanations but best check basics first……clean fuel with no air is essential. FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

This is driving me nuts now,,,,
First thing on a morning even in freezing temperatures it will start without hesitation and run perfectly. I can drive for miles with no issues even though I can clearly see air going round in the fuel line's. If I turn it off it absolutely will not start again until I go back to it many hour's later. It will then start again no problem

I would look closely at the rubber seals on the filter/pipe connections, is the filter a genuine one? 2013 FL2 XS.
Defender 90 300 TDi.
Defender 90 300 TDi CSW.
1964 MGB Roadster.
1944 Willys MB "Jeep" with bullet holes. (gone)
17 hand Irish Drought Thoroughbred (mostly lame)
Nagging Old Boiler.

Mahatma Gandhi said if there is an Idiot in power those who elected him are well represented. The Enemy is our own corrupt Government.

After all this time and problems it must getting to the point where it is worth changing all the fuel line and components from Fuel Tank to HP Pump. --- Time is Money --- FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 79k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

It's a genuine filter just fitted this week, all the o rings look good in the lines. The previous filter was a Bosch and only fitted at the beginning of this post.
I've swapped the line from filter to HP pump so I'll look at the line from tank to filter

Well that's me beaten and giving up I'm afraid.
I've swapped and triple checked everything. I've even put a full length of hose from the tank straight to the HP pump and it still won't start once warm. It just cranks over for ages.
So it's unfortunately going to the scrap yard

Sorry to hear about your woes.

Did you still see bubbles with the hose bypassing all the filter connections - going from tank to HP pump ? Jules

I can't let a FL2 die.

Have you tried all the listed items in the Repair Manual?

(ignore the highlight -- product of my searching Manual)

 FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 79k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)