95 E320 Cabriolet will crank but not start...
 

Has been sitting in storage last 45 days, last time started with difficulty but never any starting problems prior to this, has 89k. Fuel relay appears to be clicking so I'm thinking it's electrical rather than fuel, battery is rock solid, just will not fire at all, one odd thing though... The tach bounces around erratically while cranking from 500 to 1K rpm with no rhyme or reason so I'm guessing OVP first based on that. Next logical candidates might be MAF/MAS or maybe CPS (just had one go out on my 211). Big problem is no access to do normal trouble shooting without towing the car, so hoping for a quick lucky fix without throwing a ton of different part$ at it. Anyone else have similar experiences with their Cabriolet or M104?

With the tach bouncing, I would start by checking the flywheel crank sensor.

If that checks out good, then the OVPR.

Just to confirm.. crank not cam...correct? Also the catalog shows two different types, one that includes the wire for early engine builds one without for later builds. I assume mine is the latter but will go make a trip to the car and check to confirm. Any experience on failure rate for either one? I think I will just replace rather than test due to the storage cramped quarters and the part being relatively inexpensive. I have done dmm tests before on voltage regulators and other components that checked out ok but were in fact bad after all.

hello ggustaf,

keep it simple, and start with the basics:
1 pull codes
2 listen for fuel pump(door closed, seat belt buckled= to avoid buzzer). with key on engine off, make sure you hear the fuel pump whir a couple of seconds
3 check your spark plugs for: condition, gap , and look for nice blue spark

if all of the above checks out, it could be the crankshaft sensor , i had mine replaced @around 100,000 miles.

and from what i've read on the forum, if you still have the old style OVP in your car, it would be a good idea to replace it with the newer updated one, as preventative maintenance.

OLD style OVP = 000 540 52 45

updated/revised OVP = 000 540 67 45

good luck

my 95 e320 wagon did that. The ovp is behind the battery on the right. It has a fuse (non german) on top of it. Pull that relay and wire brush the contacts....reinstall and try to start. Fixed it for me.

Was finally able to get back to the car today to get the engine vin for proper sensor and pull codes. No faults on the led, just one flash, maybe no codes due to battery being disconnected and not started since? i'm leaning towards just replacing both ovp & reference sensor regardless, any other ideas?

Just replaced OVP and the car started immediately...I have replaced at least 5-6 OVP's on my long time fleet of 124's with 103's all with the usual symptoms, but never with a no start condition alone like this one without the usual warning signs. I guess the 104 is a totally different beast... Hopefully no wiring harness issues down the road...My car was built in 11/95 and sure enough the OVP had a build code of 11/95. Thanks for all the suggestions!

hmm...must be the 104 that fails this way. How corroded were the male connectors on your old ovp?