1995 E34 M540i/6 stalled. not able to start it again

[nuts4bmw]

• 1995 E34 540i
  
  
  I hope someone here can help.
  
  My car stalled and I was not able to start it again. Crank, crank crank, no start.
  
  Pulled the fuel pump, bench tested it and it runs good.
  Put it back in the car, but not into the tank. Plugged it in, and hooked up a test light directly to the pos and neg. terminals on the pump to check current flow. Turns out, the test light only lights up intermittently.
  So I checked the fuel pump fuse, and pulled the fuel pump relay, Fuse is good, relay is also good. Try starting car again with test light still hooked up to the fuel pump terminals, and now shows a constant light while cranking motor. Screw everything back together, crank the engine, and it fires right up. Turned it off and restarted it over a period of a couple of hrs, and it fired up every time.
  
  This morning, no start, again and again.......uhhhhrrrr..... frustrating.
  
  I read in another thread fuel pump related, that is the crank positioning sensor is faulty, no current will be sent to the fuel pump.
  
  So, how do I test the CPS if it is good or not? will a bad camshaft positioning sensor also cut off current to the fuel pump? How do I test one of those?
  
  Electrical trouble shooting is my weakest when it comes to repairs. Any help will be GREATLY appreciated! Thank you in advance.
  
  Art
  
  
  
  
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[shogun]

CPS Testing: The sensors has a resistance of 540 +-10% ohms between PIN 1 and PIN 2. An infinite resistance is measured between PIN 3 and 1 or 2. Connector pins shown here http://www.e32-schrauber.de/bmw/date...or_Stecker.png
Using digital multimeter, check resistance between terminals 1 and 2 in crankshaft position/rpm sensor connector.
Crankshaft Position/rpm Sensor Specifications
• Coil resistance (approx.) @ 20°C . . . . . . 540 ± 10% Ω
• Air gap (sensor distance from toothed wheel) . . . . . . . 1.0 ± 0.3 mm (0.04 ± 0.01 in.)

[nuts4bmw]

Thank you very much shogun. Your help is greatly appreciated. Stay tuned for updates.

[///M3 Reddog]

I had the same issue and it took me way too long to get it resolved. Brought it a BMW mechanic (or so I thought) and he focused on the fuel issue. In the end I got a crankshaft sensor for free at the junkyard and it started right up.

[E34 Lives]

Not knowing how long a crank sensor can last, I decided to change out my crank position sensor that goes into the front of my engine block as basic maintenance at 150K miles. I noticed the new replacement part had a plastic exterior housing. The old one was all metal housing. After, few years of service, I notice the plastic cased crank sensor developed a bad oil leak, so I pulled it and replaced the O Ring, but it still kept on leaking because the plastic housing was warped and could not seat flush with engine surface to maintain a seal since it was only held in with one screw.

Luckly I still had the original crank sensor with the metal housing, swap that out and resolved the leak. Always buy the part with metal housing if available, those plastic casing parts just does not hold up compared to metal casing parts.