Saddle tank not refilling itself.

[Mickey42]

CLK 320 petrol 2004. I’ve replaced both units in the tank with new and aftermarket fuel filter. Fuel lines have been blown through too yet the driver side of the tank will not fill. I really could do with some advice on this please. Thanks

 

[Doug1234]

This link is from an alternative fuel forum (vegetable oil) ,the forum it is on runs out of bandwidth about half way through the month so by say the 13th or just after it will be gone until the 1st of next month.
Anyway this is the best saddle tank info you will come across

A possibly easy and non invasive remedy for the notorious saddle tank problem on the Merc C250 running on VO?

 

[NJS5]

I think the answer is in post 10 in that thread; which was my first thought:-

Why not fit a small pump, pumping out of one side and into the other?

Re-routing the return to the same side as the fuel feed should have exactly the same effect, but be completely reliable.

Though I can see that some fuel is going to spill over into what used to be the return side (and which now is exclusively supplied by either the fuel filler neck or just the balance pipe) and may get trapped. However it will be trapped on the cold side, so the level in the feed tank will be higher and stop you running out of fuel.

NJSS