Very Good.....

The OVP is a "Dandy" little troublesome smart fuse that took it's toll on many a false diagnostics..so those in the know always start there first on the full electonic versions.......................

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A Dalton

I am jumping on this thread as I am using it as my reference with my present problem on a 1993 300e-2.8 that has been with me since 2005. Also, since Mr. Dalton has been replying on this thread, I might have the chance to get his VERY important inputs.

This is my first stall that required towing back home, all of my issues have been fairly ordinary auto problems, such as dead battery, broken relay for power seats, wiper arm issues, mechanical and some small maintenance issues. The wiring harness and ovp have all the new correct part numbers and it is only the ETA that I cannot confirm but it looks like it has been rewired as I can see ordinary electrical tape wrapped around its wiring.

Aside from the rare occasion of idle surging (idle upto 1k-1.5k rpm), the only issue I have related with this, is its intermittent stalling and restart when coming to a stop or upon disengaging my foot from the gas pedal, which it has had since I got it. I have gotten used to this that I would normally just coast and restart with no problem and I am ok (though it would catch me sometime on inclines and that's when it's really a bummer) I have always blamed the poor gas quality in our area for this as much as I blame it on my gas mileage (16-20mpg city driving, am I asking too much :-) ).

All was ok, until last monday morning driving towards an appointment that my problem started. I was coming from a stop turning left on the main highway with traffic clear, I decided to give the car a little run, I stepped on the gas and after a few blissful seconds the car suddenly stalled, I tried to restart it a few times but it wouldnt run.

Upon coasting to a stop on the road side, I tried to restart, cranks but no run. I tried to tap the OVP, start it, turns over but no run. Called up my mechanic for SOS, but he was out of town on another SOS, he instructed me to wait a while before I try to restart. I dont know how many minutes or seconds I waited but it wasnt too long and I tried again but no run. Since I was just a mile away, I called home and asked to be towed back. When we got home (less than 30minuts since stalling), I tried to start it, and voila it starts, I let it sit for a few minutes and parked it in the garage. Next morning I tried it again so I could bring it to the shop, first start it fired up but died after a few second, second try it would turn but no run. Mechanic came in by lunch time and after looking at the FPR he asks me to start but no run. He smacked the fuel pump as he claims not hearing them the first try then asked me to start the car but still no run. I asked him if he could try to jump the FPR just to confirm but he flatly declared that I should order the 2 fuel pump and the fuel filter already and he'l be back to install them.

I begrudgingly agreed but didnt do as he asked. I went to the computer and started my search on this forum just like before for a deeper understanding and some help.

So far I have jumped the FPR and heard the pump preload the system, since my mech claimed that he didnt hear them yesterday, I bought a new FPR thinking that it was all that was broken, I installed but still it just turns over but no run. This morning, I proceeded with the OVP, I checked pins 86 & 87 with a bulb tester and it would light up but not for more than 2 seconds. I was expecting it to continuously light up until I turn the key off but:

1.) is this already a clear indication that the OVP is ok?

Where do I go from here? I am just about tempted to throw a new one in just to be sure, though prudence tells me to save up for a more catastrophic end result (fingers crossed).

2.) I am thinking that I should first make sure that there is gas reaching the rail. Would a working primary pump indicate a working 2nd pump or not necessarily?

3.) The fuel filter has less than 4k miles on it for sure, should I change it anyways as I check the 2nd pump?

4.) Any other component that's involved in this kind of turns but no start problem? The MAF or ETA or coils or injectors come into my mind.

This is going to be my first DIY, so please be gentle to a newbie :-)

Add the Crank Sensor ("Crankshaft Position Sender") to your list of items to check. Your stalling sounds like it *could* be related to engine temperature.

A simple way to check is to start the car in your driveway, let it idle, and find something else to do (nearby) for a while. If, after it gets hot, the car stalls while idling, the crank sensor could be at fault.

But the electrical tape on your ETA sounds more worrisome.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Thanks Eric, i'l keep a tab on it, I hope to start on the car soon as more info comes in. engine temperature though has been in normal range specially after the new overflow tank fixed the cracked old one that negated the benefit of the relatively new radiator, now I sit confidently even on bad traffic without worry of overheating.

There is no 86 on OVP

Follow these steps IN SEQUENCE

These have to be done when condition is present b/c you have an intermittant condition.

Remove FP test plug from rail and install a gauge.
Remove F Pump relay and jumper 30 and 87 at the connector [ 3 & 1]
That is pumps , direct..do you have a gauge reading?

If yes , pumps are OK
Remove jumper.

Key ON , take a V reading at 85 & 86..[4 & 5] . 86 will be + for meter leads...or just use a 12v test lamp. Hook test up and then turn key ON.

Voltage w/key ON ?

Re-install relay.

Key On...Spin fuse # 6 in it's holder.
Gauge reading?

Look at OVP ..you should have pins 1 and 2 [ 30z & 7U ]
Do you see them?

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A Dalton

First, thank you Mr. Dalton for the time !

I'm sorry about the miscue on "...proceeded with OVP, I checked pins 86 & 87 with a bulb tester ....", what I meant was checking OVP 12v input at FPR socket where pin 86 & 87 inserts, my bad !

I'm going to follow your instruction chronologically tomorrow morning, the only item I'm concerned now is what kind of gauge I could use for the fuel pressure at the rail, would a common water pressure gauge be suitable, I havent really taken a look at that part to sensibly think of what can be used, sorry if its a dumb idea.

I will post results immediately after checking.

Any pressure gauge..and an old R12 hoses works b/c it has the schrader valve release pin.

You do not have to go to he rail ..it just makes it so much easier than to go checking the pumps with each test.
And a bad connection will show immediately
These are jsy my procedures ans I go the most effective route.
My suspect is OVP or fuse 6..but I have to check these first b/c yor guy diagnosed pumps, so I have to secound opinion him. He may be correct.

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A Dalton

Hi everyone, had a family emergency, my wife and I needed to attend to her mom as she underwent heart surgery.

Today's my first chance to look at the car and the results are imbedded at the quote above. Thanks to all specially Mr. Dalton in advance.

update: i removed ovp and decided to run to nearest parts store to get a new striebel ovp, installed it and tried to start the car- still turns but doesnt run ;-(

Anyone thinks the igniion coils or plugs are suspect now with this? I failed to mention I had a new battery delivered yesterday morning before I started the test, just in case it matters mentioning, my old battery drained itself from the previous tests and its about time anyway to replace it.

Maybe its also time to build the code reader too just in case, while waiting for any suggestions from our gurus.

update:
I was able to do a couple things, I decided to change the bosch super plus plugs with the f8dc4 plugs i've been meaning to since 6k miles ago when the mech installed them, car was running fine so the big delay installing the proper plugs, result: still turns but no run.

Next I had stashed a complete set of coils in my closet and decided to do a rolling replacement of the old ones from #2 upto #6 attempting to start each time but no success. I then installed all 3 new coils with new boots with no success either. So much for my plugs/coil theory. I also tried on the new plug wires with the same sad result just as the sun set on the horizon along with my hopes to revive it today.

Anyone out there who can point me to a ''learned'' direction to what I should have done or what to do now? Or even just a plausible theory on what's going on? This is the first time in 4 years that it has not started in one click with a good battery.

Not sure if the '95 has a disabler on the alarm, if so have you tried locking/unlocking the car? Should tell you in the manual under alarm information.

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Gone to the dark side

- Jeff

thanks baabymog, I appreciate the input.

Yes the alarm did cross my mind so yesterday I cycled the driver side door, I will go over the manual just in case I did it wrong.

Any MB tech out there who could chime in and spare a few moment to help out a guy this side of the planet please!

ATA on that chassis should only have starter interlock w/K38 relay.
I would check the Crank sensor .
..and get the codes , specially at HFM module [ [pin 8]

Does FP at rail come up when you turn the key ON ??

You mentioned that you had done that test before , but you had residual pressure from the relay jumper test..the test you want is to bleed off any rail pressure BEFORE the key test..... If no PSI then , then you have a feed problem to the ECU..

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A Dalton

hi everyone!

I consistently get 60psi at the rail every time i turn the key on, after attempting to start it would drop to about 53psi. When I leave the car for a few hours, i would find the gauge at zero psi, I assumed it was because the fuel has exited back to the tank (i remember the rail has this ability). Since I installed the gauge 3 days ago, every morning before I'd work on the car or just look at it, I would find the gauge pegged at zero too.

I hope to build the code reader soon as I get home in a few hours and report what's stored immediately. Also I will bleed off the gauge to remove residual to re confirm pressure at rail before and after turning key on. Thanks so much for the ''push'' guys! Keeping my fingers crossed for now.

Good day to everyone, got a break from my work and was able to build the code reader and late this afternoon, I tried to retrieve the codes which are as follows:

DM CODES
# 10 Voltage at Mass air sensor too high/low
# 12 Heated oxygen sensor heater circuit open or circuit short
# 17 Data exchange malfunction between individual control module

PIN 6
# 3
# 8

PIN 8
# 13 O2S (lambda) control system operating at rich or lean limit
# 42 CAN communication from ASR, EA/CC/ISC module or diagnostic module (OBDII)faulty

PIN 14
# 5 Stop lamp switch (S9/1)
# 7 CAN data bus signal from EA/CC/ISC, ABS/ASR, HFM-SFI (right or left) control module faulty

I dont have the code list for PIN 6 yet, I am trying to find them as I type this now, I dont even know why I checked it, I was just trying to get as much info across the thread for better perspective, if anyone has them please kindly fill up the blanks for me, thanks.

Also, I am not sure if I was able to erase the codes, when I bring them up and erase them, they would still reappear after I lift the button for the 10seconds erase on the last code of every pin. I dont know what I am doing wrong but Im following the instruction as I understand them, any tip would be much appreciated.

Lastly, after I got the codes, I disengaged the FP gauge from the rail and drained the hose to remove any residual, reconnected the gauge and turned the keys on, I got 60psi then it drops after 3seconds to 53psi. (I tried to start the car, still turns but no run)

Let me add for more perspective, that when I got the car, the exhaust system was converted into a non-catalyst/no O2 Sensor system. What I had ask for the mechanic then was, to weld a nut into the pipe where the catalyst should have been so that we could install an O2 sensor. This would be no more than 20k miles ago, maybe the O2sensor has gone "kaput" I dont know and is showing the rich/lean mixture. I also could wager that the absence of a catalyst is the reason for this, it could have fried the sensor altogether. Could a California version run without a catalyst and not throw any codes or problems?

I am at the moment feeling very uneasy over the recurrent code from each pin of the faulty communication between modules, it sounds like big $$$ !!! I hope the ECU is not fried or something really major.

Well I hope to continue my DIY tomorrow should the gods of peachparts send their graces to me tonight

ps
If anyone can me tell how to check the CPS, please feel free, that's one assignment I havent done yet, I will of course search the forum for this, but just maybe someone doesnt mind giving me a little push on that subject, just maybe

edit:
the more I read about the CPS, the more I am leaning towards it, remember that before this episode it was preceded by the stall at highway speed and previously have been having stalls but quick starts? I hope to find the method in diagnosing a bad CPS so I could report back as per Mr. Dalton's instructions. Fingers crossed.