Dies suddenly, then no start - FIXED

[AndrewBird]

I was driving home tonight in my 94 525ix touring and while sitting at a stop light, the engine died and would not re-start. No signs of any problems before hand, just running one second, then off.

Things I've checked:

Fusible link - Not broken and everything else electronic still works.
Intake boot - No cracks or tears
CPS - Measured 579 ohms. Looked a bit gunked up with dirt so I cleaned it. Gap to sensor wheel looks good.
DME Relay - Pulled it out, took the cover off and cleaned the contacts - Also tried junkyard relay
Fuel Pump Relay - Pulled it out, took the cover off and cleaned the contacts - Also tried junkyard relay
Visually inspected for vacuum leaks - Nothing obviously visible.
Engine ground - Dirty, but intact. Also, it wouldn't crank if bad, so that rules that out.


When I try and start the car it will almost catch with no throttle, but only occasionally. If I give it any throttle, it will only crank. When I pulled the intake boot, it was wet inside with fuel. The exhaust tips also had some fuel in them after trying to start it several times, so I obviously have fuel. I didn't check for spark yet, but I can't think of a reason why I would have fuel but no spark. Right now I am thinking vacuum leak. Going to build a smoke machine and see if a smoke test reveals anything.

Any other ideas?

EDIT: Checked for spark and I do have spark.

[5Toes]

Check your MAF and ICV - my car had a similar issue and cleaning those two things fixed it good as new

[e30austin]

Unplug your MAF and see if it changes anything. If not, try o2 sensor.

[golde30]

TPS went bad? dunno if that would cause a no start...

[AndrewBird]

Was able to work on this a bit. Pulled the MAF to clean it and managed to break it (ARG). Got another one from the junk yard, cleaned it and put it in. Car started and ran for a few seconds, then died and won't start like before.

Tried a different DME from the junkyard, no difference. Also tried main and fuel pump relays from the junkyard.

I did check for spark and I do have spark, at least on the number 1 cylinder where I pulled the coil. Didn't check every cylinder.

Any info on checking if the coolant sensor is bad? The Bentley only has info on replacing it. Might just throw a new one in and see, they are cheap.

At this point, I think I'm going to have to pull the intake manifold and look for vacuum leaks.

[e30austin]

Interesting on that maf issue. How do the wires look at the end of the plug? Not shorted out or anything?

Your car is a '95, I'm betting that it has a silver label DME. If so, you can't just change them out as they are specific to each car due to EWS (if your car is a red label car, disregard the aforementioned info.)

[AndrewBird]

My car is a 94 and has a red label dme.

[e30austin]

Oops, thought it was a '95. My apologies.

[AndrewBird]

FIXED!

Ended up being a bad fuel pump. Must have been working intermittently as I had fuel at one point, but then none later. Also replaced all the fuel lines, the fuel hoses, vacuum hoses and the intake boot. Very happy to have my car back!

[bmwsun]

I am having a similar issue with m50 non vanos wagon right now. I think it is either the CPS or fuel pump relay....