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1990 W201 2.6 M103 3.0 (103 983)
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Discussion Starter · #1 ·
So basically I've been trying to get this car up and running and has been going well for almost a year now already passed inspection and all , but recently the car for some reason had a short , I went digging up the car electrical wires and found out the fuel pump housing was damaged and all the pins fell out of the holder , i've searched all over the possible site for a pinout diagram i was able to connect few wires however few of them i couldn't find anywhere on sites. just placed them in random order and the car starts fine idles fine, however when i put the car in Drive it idles fine and will drive fine on the engine rpm but when you touch the pedal the car act like its about to stall, and it does when you keep holding the pedal even ever so slightly. I've checked the TPS , CPS , EZL , EHA , potentiometer, Fuel pump relay, i just can't figure it out what's causing this.
possibly the short damaged the ECU ? , the ovp seems fine even replaced it same issue.
FYI : the car has been restored so most parts are new
# fuel pumps
# injectors
# spark plugs
# Distributor cap and rotor
# Spark plug wires
# Fuel Filter and accumulator
# Fuel Distributor

I've included two pictures of the current wires for the fuel pump relay in the order I installed.
only one side was damaged the other side is still intact as it is.
Also a link to a video I took that explains the issue.
btw don't mind the fuel level my fuel level sending unit isn't working and the car does have almost a full tank , and the hand break light just to demonstrate how the car act when it's under the slightest load
Video Link: 190E.mp4
Electrical wiring Electrical supply Electronic device Wire Cable

Glasses Wheel Tire Automotive lighting Automotive tire
 

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1992 W201 1.8 Automatic
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207 Posts
armchair busybody/weekend / self-taught mech here... Am wondering if the Idle control valve is closing when it should be opening when put in drive... Obviously I know nothing about the wiring, Just my 2 cents, hope it helps, cheers, let us know it goes
 

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Registered
1990 W201 2.6 M103 3.0 (103 983)
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10 Posts
Discussion Starter · #4 ·
armchair busybody/weekend / self-taught mech here... Am wondering if the Idle control valve is closing when it should be opening when put in drive... Obviously I know nothing about the wiring, Just my 2 cents, hope it helps, cheers, let us know it goes
Thanks for the reply I did check the voltage to the ICV and it seems to be steady not affecting the car in a matter of making it stumble. something I noticed that the car doesn't show any issues when first started cold for like a minute or so , afterwards it behaves as shown in the video.
 

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1990 W201 2.6 M103 3.0 (103 983)
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10 Posts
Discussion Starter · #5 ·
Was this engine fitted later on in life i know that the m103 engine was a normal engine but not the 300 .So what engine was in this car from new ?
The car was originally 2.6 with 75k km imported from japan and has been sitting here for like 20 years or so, currently I swapped the engine due to it being super rusty inside and out , seems like someone placed normal water in the radiator and with years it destroyed it inside out, I swapped it with m103 983 from 300CE. It was direct swap pretty much everything just plugged right in and ran beautifully.
 

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1990 W201 2.6 M103 3.0 (103 983)
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10 Posts
Discussion Starter · #7 ·
Update: So basically I tried to put the car on jack stands and see if it does have anything to do with the load on the engine and it seems about right, when the car on jack stands it runs absolutely fine , no issue showing , shifting into D and running it , shift gears fine , runs fine , no sputter or hesitation or any issue what so ever. the question is what possibly could be the issue now that I narrowed it down to load on the engine, Is the car not richening up the mixture in order to compensate for the load ? , or is the EZL not registering the car is under load in which it adjust the spark ?
I'm open to listening to any ideas.
 

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1990 W201 2.6 M103 3.0 (103 983)
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10 Posts
Discussion Starter · #9 ·
Update: I spent almost 2 days just focusing on the car to get this thing back on the road, and glad to say I solved the issue. In my case it was a combination of two issues together ( I guess ). The first one was the ground wire, as I mentioned before I ran through a short which affected the cluster and signal. used a multimeter to check the ground on the fuel pump relay and the ground wire seemed to be fine but out of curiosity I added an extra ground wire to the existing one. I'm not sure where does the ground wire from the fuel pump relay leads to but I assume there is a short in that wire. Second issue I found was the CTS wires were exposed at the top of the connector which may have been touching and affecting the car (not sure) but taping those two wires + adding a ground wire to the fuel pump relay seems to fix the issue.

as for the car running fine on jackstands i would assume that due to bad ground wire the fuel pump was supplying just enough fuel to run the car without load on the engine, Just guessing not sure.

and btw the wires in the pictures I submitted above are indeed correct for anyone needing them in future reference.
thank you all for the help.🤝
 
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