Have a meal with each other, I need a little help from ‘old hares’ here! Have a real rarity from my stepfather, an 1980s M535i E12. The car has stood up to last week a good 15 years. Now I have brought the good piece back to life and when it runs it is a dream to drive with it. The following problem…the fuel pressure and the circulation falls together as soon as the car has stood 3-4 hours. which is the backflow line on it. Has the now certain time stood, even with the running engine no fuel can pass there. Follow engine runs bad until it even does not run anymore because of lack of fuel. I renewed all fuel hoses, pump runs. The last days I proceeded as follows to have the engine run reasonably. 1.Relais the pump bridged so that it runs through. 2. Return hose and piece hose to the pressure regulator and neatly with the mouth ansa until the fuel has arrived after 20-30sec, quickly return hose on it again. Then it purrs like a chick and everything is good. You can also put it off for 30min to shop and similar things…But if it takes 3 hours then the whole procedure from the front. What’s the matter? The pressure regulator? Can you check it? Somehow something still clogs or leaks? Nanometers for the pressure test on the inlet side unfortunately I have no… But as I said, the circuit is once hung If you leave without doing that in the morning, you will be left behind after 500-600m for lack of fuel and there is nothing left. Who still has ideas to do with it? Thank you!!!