Hello, Thibaut, stuck in France here, my 240 GLT/B23/ LH2.4 was resurrected after a long period... started with the crankshaft timing sensor replacement (easier said...), started straight away, now the issue is a no cold start at all.

Checking the fuel line, uncoupling the return line from the FPR into a jug it started straight away, I then blow the return line, reconnected, restarted and after a couple minutes it just died. Uncoupled the return line, noticed it is under some low pressure (?), attached a transparent tube to the jug, plenty of air bubble.

Reconnected the transparent tube to the return line, plenty of air bubble, and it stalled again... It seems it only works when there is no back pressure at all in the return line?

There is no gasoline leak from the FPR (standard 3.0 bar 0280 160 294) to the vacuum hose.

Question is: is it normal to have some level of back pressure in the return line?
Should I go straight and replace the FPR which should handle some back pressure?
Anything to do with the amount of bubbles in the line?
Are they an issue coming soon with the pumps/filter/lines?

Beforer investigating the tank, fuel lines and various item with poor access, I thought it might be a common issue...

Thank you for reading and some tips to avoid newbie's errors.