I made a custom tool for removing the big rings on the fuel tank, but once I couldn't find It and used a quick fix that I recommend for everyone else.

Take a bar of metal can be almost anything that is under about 1/2x1/8" flat or 1/4" round stock (12x3 or 6mm) about 12-15 in (30-40cm) and bend it into a "u shape" where the ends will hook onto the little steel loops on the giant fuel tank nut, now put anything long enough to fit through the U and turn while holding the (upside down) U into the "nut". You have perfect precise control; no risk of cracking a 15 yr old plastic fuel tank banging on it with a hammer.

Thanks again for your helpful comments, you have no idea how much this is appreciated. Andrew, you sir are an absolute legend, spending the time to create a how to document such as that referenced. I have no hesitation in taking on the fuel pump mod you have suggested thanks to your guide.
I wasn't even aware of how to access the 'hidden menu' until reading through so i've already learnt something new, let alone now beginning to understand how and why the X5 fuel tank is the way it is.

Can you post a pic?

X5 3.0D E53 2005 Starting Problem
 

Pretty sure I have. Look at my fuel system and siphon jet threads.


https://www.icloud.com/sharedalbum/#B0SGWBC59G1ufgn

Here's a link to my siphon jet repair photo album. It has my tool and a great little trick I used when I couldn't locate the tool.

Do you wait for a few seconds (with the key in intermediate position) until the glow plug light goes out, before engaging the starter motor? In tank fuel pump and fuel sender (replaced in my car at ~290.000 km) could be an issue, typically not that soon BUT it is a wear item and easy to replace (easier and less messy with less fuel in the tank).

As you have NO history, good to also change all filters and fluids, including transmission, transfer case, differentials and even power steering fluid. These aren't related to your immediate issue (unless your fuel filter is part of "deferred maintenance"). You'll want to see if your breather (when you replace the air filter) is the older "loo roll" style, in which case you will want to update to the vortex style (I can advise you the specific parts - I'd need the last 7 digits of your VIN).

What glow plug light?

Do the pre-facelifts have a glow plug light? The LCI models certainly don't - only a text message on the dash display and even then, only under one very specific condition.

On the LCI, the glow plugs operate thus: -

A short pre-heating cycle (2-8 seconds) is used any time the engine is started with the coolant below 30DegC. This is a silent cycle - no message.

The glow-plugs are activated if the engine coolant temps fall below 75DegC while running. This is a silent cycle - no message.

A long pre-heat cycle (10-20 seconds) is run at start up start-up when coolant temps below 0DegC. - coolant temps, not ambient - and this cycle is indicated by the "PRE HEATING" message on the dash.

This last condition - coolant temp lower than 0DegC. - is the only time an LCI owner wil see anything related to glow plugs on the dash. I see it only a handful of times a year...

Hard starting on an M57 is very rarely related to glow plugs, even in cold weather (extreme cold weather aside!).

Poor running, excessive fuel consumption and excessive exhaust soot are indications of glow plug problems. A failed thermostat can lead to premature glow plug failure, as the coolant remains below 75DegC. for considerable periods, extending glow plug activation and shortening their operational life.

Problem Solved
 

Well, after a summer without the problem showing it's head, the mornings have now dropped in temperature and the problem had returned.
I bought a replacement relay for the fuel pump (located above the fuse board behind the glove box) and fitted that on Sunday. Monday morning was the coldest of the year so you can imagine my delight when it started first time, no hesitation. Such a relief to have sorted the problem with a £6 relay and 30 minutes of my time.
Thanks again for all of the helpful comments
:thumbup:

Thank you for the update,
This is good to know.
Did you replace with a OEM relay or something different?

It was a new, genuine BMW replacement part but purchased from a well known auction site so not 100% sure...
It did look exactly the same as the old relay though.
So pleased after hearing so many horror stories of BMW taking weeks and charging extortionate amounts for what sounds like a very similar issue.
:D