BMW Repair: 1989 525i, fuel pressure gauge, fuel pressure regulator

Question
has anyone had experience in dealing with a "hard to cold start" problem"?  runs fine otherwise - cranks strong - starts fine warm  

- thks

Answer
Hello Ellis,
Chances are that you have a bad fuel pressure regulator.
Of course it can still be due to another thing but this is where I would recommend that you start to look at.
Diagnosis would be by connecting a fuel pressure gauge in line with (before) the pressure regulator. After starting, since the engine runs fine, then your fuel pump is normal (it should read approx. 35-45 psi). But once you turn off the engine, the fuel regulator may be letting go of all the fuel pressure so that the pump has to build it up again before it can supply the fuel injectors and start the engine. After turning off the engine, fuel pressure normally goes down but residual pressure should stay at approximately
10 psi. This item is not that costly and is very easy to install. It is found at the left hand top side of your engine. You may want to replace it even without a lengthy
diagnosis.