1990 300SE (W126) Stalling issue (OVP?) - PeachParts Mercedes-Benz Forum

tinypanzer · #1 12-29-2008, 09:07 PM

Hi all,

Well, after reading all the posts about the OVP, the next day my car started stalling mysteriously. It has only stalled 3 times total so far, so it's sort of hard to pin down.

It has only stalled (so far) when I am decelerating to make a 90 degree turn. Twice on a right and once on a left. It stalls about halfway through the turn leaving me with power steering by Armstrong to finish the turn.

It starts back up immediately, with no struggling to ignite. It then continues to run just fine......

I do not know what indicator lights may have been involved because I had my instrument cluster out to repair the odometer at the time. Yes, I did plug the vacuum line to the economy gauge so that isn't the issue. I do have my cluster back in now.....

Sounds like a typical OVP issue based on what I've read here, but I'm not sure and at $85, it's not something I want to just replace without knowing for sure....

Any advice or test procedures would be very much appreciated.

Thanks!

-tp

mak · #2 12-29-2008, 09:38 PM

Most likely its the fuel pump relay; you will need to resolder the solder joints at the same time do resolder the OVP joints.
Cleaning the I C Valve and the inside base area of the intake will certainlly help.

regards
mak
300se/1990

tinypanzer · #3 12-29-2008, 10:08 PM

Hey, thanks for the tip. Sounds like you've been down that road before.

Where is it located? My WIS is acting up at the moment.

-tp

jdc1244 · #4 12-29-2008, 10:09 PM

90 and 91 300 SEs don’t have a stand-alone FPR, it’s incorporated in the MAS control unit between the firewalls near the OVP. Best to find a good used MAS to swap out to see if it fixes the problem before buying, they are pricey.

If they haven’t been replaced in a while I’d start with the cap and rotor. I had a similar problem and that fixed it. A dying fuel pump could also explain your problem, depending on the miles and if the car has the original pump.

tinypanzer · #5 12-29-2008, 10:29 PM

Shi#. I just passed up on a MAS unit from a junker that was the same model and year.

Better go back and see if I can get it still......

I'll check the other stuff too. Are those MAS units prone to bad solder joints like other modules? Are they even openable?

Thanks for your help....

-tp

pawoSD · #6 12-29-2008, 11:16 PM

The stalling issues I was having with our 300E ended up being the air intake temp sensor and the idle control valve.....swapped in junk yard units....works perfectly now. Issue was that it would not hold an idle under any circumstance, it just shut off if you stopped pressing the pedal.

mak · #7 12-30-2008, 09:26 AM

on my 103 .the relays are located on the firewall . OVP has a fuse on top of it
and the fuel relay is near it. As i had mentioned do clean the ICV ect.
i assume you had replaced the rotor ,cap and the leads . the plugs are the non resistor type only for this engine .

Quote:

Originally Posted by tinypanzer

Hey, thanks for the tip. Sounds like you've been down that road before.

Where is it located? My WIS is acting up at the moment.

-tp

tinypanzer · #8 12-30-2008, 03:12 PM

Hi Mak, thanks for your suggestions.

Here's what I have done so far.....

1) New Bosch Copper+Ytterium plugs (ordered them here from FastLane)
2) New Air intake sensor (old one was MISSING)
3) New coolant temp sensors (both of 'em)
4) New vacuum line elbows

I have not had the chance to pull the cap and rotor yet. I plan on doing that this weekend. I need to have money first, in case something crumbles as I disassemble. God only knows what I will find. The previous owner of my car had some very interesting ideas regarding component selection. I've had to undo many of his mistakes, my favorite of which was the battery that was so tall it shorted out on the hood. The platinum Autolite plugs were a close second. Man, they were totally crusted up and melted when I pulled them. Lucky my car even ran with them.

She hasn't stalled in a few days now, making this even more difficult to pin down. I'm also wondering if those plugs didn't cause damage elsewhere in the ignition system.

I'm gonna really dig into the car this weekend. I'll be sure to post back what I find (or don't find).

Thanks!

-tp

mak · #9 01-03-2009, 01:56 AM

Do replace all the fuses with the brass versions ,around this time the ageing fuses develop hairline cracks and cause intermittent faults .
fuel accumulator too ,especially if you notice difficult hot starts.
in tank fuel filter clean up .

tinypanzer · #10 01-07-2009, 10:49 PM

Thanks for the advice. I've already replaced all the fuses with the brass ones. That was done a while back. Haven't done fuel filters yet, or fuel accumulator but I have absolutely no problem with hot starts, they're almost instantaneous.

Oddly, the problem came on rather acutely (three times in two days) but it hasn't happened since. It's been well over a week... I'm a bit puzzled.

-tp

Michael Pillay · #11 01-09-2009, 09:52 AM

How to test the OPV (Overload Protection Relay)
It is a good idea to first check/replace the fuse in the relay.

Remove from car. It is held by a single 8mm nut and then unplugs.

set the multimeter to diode mode. Positive test probe to terminal 31 and neg to term 30

norminal value is 0.4V to 1.5V
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