Fuel tank. In the rear. Very very common that they rust out and completely fall off. There was a website once I lost the link that had a list of the most common bmw items people buy, ie fuel tank straps, fuel door hinge, side molding clips, etc! Thought it was funny.
For now the car drives amazing no fuel pump issues. It's a hard one to justify changing until it actually goes bad and doesn't start. Right now my priority is the starter. And then the radiator leaks because the idiot owner put a cheap plastic one in it so will wait till next summer money saved up.
Fuel pump, fuel pump relay. If they are so bad it's likely the previous owner changed it already. Our 420sel mercedes everything the forums said to change turned out to already have been changed by a previous owner. Funny
You said CPS. What is CPS? Is that the camshaft position sensor. What are the symptoms of that going bad? How much is it for part and to change just curious.
And my car still starts. Makes a funny noise 35% of the time try to start it. After pull key out and go to start it starts up fine so for now its working but I assume it will only get worse. I pray it's not the flywheel. Can't afford to drop the tranny, plus that part is usually expensive too. But 90% chances its just the starter!