m50 cranks but wont start

[davidflrs]

I have a 91 525 with the m50 engine.. The car carnks but wont start. The car was running fine on my way home from work one night and would not start the next morning. I cahnged the Fusible Link figured it wasnt getting spark or fuel.. Didnt work, next I chnged the fuel pump.. Didnt work, I swapped the dme with a spare I had.. Didnt work.. I changed the spark plugs and crank position sensor.. I have to look at it again but the sensor is close to touching the teeth.. I am pretty sure it isnt, anyhow Didnt work but now it feels like a car struggling to start with a bad distributor.. The coils and boots and plugs are fairly new and purchased from the dealership.. I checked the relays and fuses nothing seems blown or burnt.. Does anyone have suggestions?

[stilljester]

Did you check the ground by the hook used to remove the engine? If the ground wire is broken there your car will not start.

[Dave M]

David, you've already tried a few things, but did you:

Check for strong spark?
Test the fuel pressure?
Replace the fuel pressure regulator?
Check the poiwer supply to the sending unit at the fuel pump?

I was tracking a siminar problem a while agao and found it to be a corroded wire at the fuel pump sending unit (easy fix). I just tried to find the old thread, but couldn't. I'll add the link if I find it. Although the relays (DME and Fuel Pump) look 'OK', they may be bad. Assuming you spent money on the fuel pump, plugs, CPS etc., you've blown quite a bit on this issue already, so you may want to try starting with some basic stuff like the spark and fuel pressure checks.

Good luck,

Dave

[Dave M]

link to old fuel pump power supply fix (http://www.bimmer.info/forum/showthread.php?t=30111)