PeachParts Mercedes-Benz Forum - W126 Not running right

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Being a 103 engined 300se . i would place the following check order

fuel filter
fuel pump relay pins being dirt oxidized
rotor resistance
distributer cap carbon contact.
fuel accumulator
speculatively i would say the relay is operating erratically.

mak
300se 103

Quote:

Originally Posted by C Holmes (Post 2556855)

You know mine acts like the car in the vid. Mine will start though so maybe just a difference in the degree of failure of the coil. I can test the coil to see if it is OK as well as the Fuel flow and filter. It is also about the way coils fail, kind of all the sudden.

Yes... our car in the video did eventually start back a few days after this video was shot. It took a few days though. I guess where it was not getting power at that time it was flooded. It did finally start and would idle for 10 minutes, but as soon as you pressed the gas down, it would start missing and stalled out. New coil was installed and never anymore problems... so far. We were also told to check things like the fuel pump, fuel pressure, spark and the FPR by bypassing it and all checked out OK. You may want to try the simple things first before replacing the coil. Like I said dad tested ours with the coil off of my 72 Chevy Caprice station wagon.... dont know how, but he did. :o

Now we have a leaking EHA valve and had to order another one. Hopefully getting this car back on the road soon.

Um, I will have to look and see which one the fuel pump relay is. Its one of those relays in the middle of the firewalls. There is a way to bypass it to test. I will see if I can find that old thread.

Quote:

Originally Posted by C Holmes (Post 2557973)

Which is the FPR?

Your car actually has a MAS relay. I have a 1990 300SE and just replaced mine. I was having similar starting issues before I replaced it.

If you remove the relay you can jump pin numbers 1 and 2. They are the two large ones on the far left side. Now, remember that left means driver's side, not on your left as you're facing the car. The MAS relay is the large relay that has a knob on it. You just have to turn the knob counter-clockwise in order to loosen it. Then, just pull the relay straight up. If, after you jump those pins, the starting issue disappears, then the relay is the culprit.

The drive-ability of a 103 engine is definitely effected by sulphated battery and especially a marginal alternator which cuts of the red warning light but hovers well under 13v under load conditions of lights, A/C and wipers.
mak
103 300se

I should mention it doesn't seem to be charging at the moment