More W124 stalling problems - PeachParts Mercedes-Benz Forum

W126Ken_W.Pa · #1 03-20-2011, 02:36 AM

I just got a 1989 300E, with a really nice clean, rust free body to use as a daily driver so I can keep my 126 and 107 in the garage until the weather breaks.
Anyway, the car has sat since 2008. at least that is when the inspection expired. I changed plugs, wires, cap, rotors, Overload relay, fuel pump relay, EHA valve , checked and or replaced vacuum lines, fuel filter (which was pretty well clogged), and just about every other sensor has either been checked or replaced.
It will idle and rev up perfectly in park or neutral. But when I try to drive it, it misses and stalls when coming to a stop, going around corners, or pulling into my driveway, which is on a slight grade. Also when it gets above 20mph it really runs rough and misses badly.
The other day it got up to 70 degrees and the car would not stay running for more than 20 seconds. The engine would stall, and I could still hear the fuel pump run for about another 10 seconds after stalling.
Another issue is major carbon buildup on the plugs. I took out the plugs and they were covered with black carbon, but dry and not wet. They carboned up within about 5 miles tops. I have been contemplating pulling out the fuel accumulator and checking that and the fuel tank screen. Could either of these be the culprit? Anyone ever have a fuel accumulator clog?
Anyone out there have any suggestions, or have had similar problems? Can anyone help? I would like to avoid at all costs taking it to the dealer since they are over 40 miles away and it will require towing.
any help would be great! Thanks!!

Aquaticedge · #2 03-20-2011, 03:03 AM

check the tank screen first. if it's clogged then fuel starvation, then move up the line. may want to consider having your injectors cleaned up too, sitting for so long they are undoubtedly gummed up, or swap in a spare set if you happen to have some there-

W126Ken_W.Pa · #3 03-21-2011, 02:56 AM

I pulled out the fuel pumps today, and one was seized up. I could hear it just humming instead of running when powered up. I am in the process tonight of flushing them and hope to get them back in tomorrow. So , hopefully this solves my problem. Thanks to everyone who posted or emailed me

W126Ken_W.Pa · #4 03-24-2011, 02:18 AM

OK. TIME TO PULL OUT MY HAIR....
Changed the fuel pumps and filter AGAIN and it ran and drove down my street, but on the way back it started acting just like it did.
What now? What AM I missing? I need help

lsmalley · #5 03-25-2011, 12:42 AM

Did you check the ovp? also, try a quick sea foam flush to clean up the the entire engine/intake.

W126Ken_W.Pa · #6 03-25-2011, 09:56 PM

It just keeps getting better and better. OVP relay is fine. Ran some sea foam and still nothing.
So, I pulled out the rear seat to fix another issue, and noticed the connector that comes from the harness to the fuel pump was corroded and literally fell apart in my hand. So I fixed that issue, the car started to run fine again. I took it for a drive up my street, and then it started acting up again. this time even worse. total lack of power. I had a hard time even pulling it in my driveway. I kept flooring it, and it went nowhere. It has a very hard time now even revving up and when it does, it now backfires into the intake.
What is going on with this car? I have checked and or replaced every sensor except the throttle body sensor. Where is the port I connect onto to check fuel pressure at the distributor? BTW, yes, I replaced the fuel distributor with a known good working one already and I replaced the entire ignition system including the control unit mounted on the front wheel well with a known good one. I've narrowed it down to three things 1). faulty throttle body sensor 2). clogged fuel tank screen 3). dirty injectors.

Anyone have any problems like this? Where do I go from here? Do I just give up and tow it to the dealer , who is about 40 miles away? or keep at it? I've just about given up on this car.

mak · #7 03-26-2011, 01:08 AM

Quote:

Originally Posted by Aquaticedge

check the tank screen first. if it's clogged then fuel starvation, then move up the line. may want to consider having your injectors cleaned up too, sitting for so long they are undoubtedly gummed up, or swap in a spare set if you happen to have some there-

Agree; A clogged tank screen will give a choked effect,check the exhaust mufflers for clogging ,a vacuum gauge will indicate back-pressure. build up.

ps2cho · #8 03-26-2011, 10:35 AM

You need a fuel pressure gauge on the distributor to see if there is a restriction backwards of the distrib.

tbomachines · #9 03-26-2011, 11:44 AM

Check the current at the fuel pumps, see if it is getting a full charge.

vstech · #10 03-27-2011, 11:00 PM

with all the carbon, I'm not thinking fuel starving, I'm thinking air...
lack of air, or lack of air flow.
air filter/throttle problems.
or
exhaust clogging...

W126Ken_W.Pa · #11 04-16-2011, 10:18 PM

I want to thank everyone who helped me out on this. I finally got it up and running beautiful. Here is what I did after everything I listed I did above. First, I pulled out all injectors, cleaned and tested them then replaced the seals. Next, I pulled the the airflow meter off and cleaned that, then removed the throttle body and did a thorough cleaning. Put it back together, and I still had the stalling issue, but it was much better than it was. I noticed that the fuel pumps were pulling way more current than they should, so I pulled them, and found one was seized up. So I replaced both pumps and my fuel filter, and now the car is running 100%. In hindsight, if I would have checked the pumps first, I would have saved myself a ton of time, and not be missing as much hair LOL! Anyway, thanks all for everyone who offered suggestions and took time to help me!!