Very strange going-ons, guys . Listen to this :Today I dared taking
my restoration project to the gas station to get gas and air .Car idles v e r y badly and stalls as soon as I touch gas. Instead of going faster the car backs down and stalls or if I let go of gas (and I'm lucky) it'll regain idle. My 560 SEL has 213K on it and
drove "ok" when I got it a year ago but had to park it for 1 year !!! Can it be saved ??? Now I can only drive it in idle .
560SEL Doesn't Hold Idle,Sometimes It Idles Roughly But Stalls As Soon As I Tap Gas !!! Hilfe Please!!!

Do all the normal stuff, like making sure that the air breather isnt clogged with a birds nest, the spark plugs and all that are ok, that its not being choked out or flooded, etc.

Then clean your Idle Control Valve. Your problem sounds vaguely like mine was, but not exactly. If you ever get it running well enough to move down the road, try to blow the cobwebs out of it. Start off slowly, and make sure that its going to actually go and not leave you stranded. Then find a nice peice of highway and do about 90mph, abruptly starting (an empty on ramp will do nicely) and go for about 10 miles or so.


As long as your engine is in good working order (no timing chains waiting to snap, etc) and you dont get pulled over, what I told you to do *shouldnt* hurt your car or you.

__________________
http://comp.uark.edu/~dmgill/signature.jpg

Pull the plugs, and view how they are burning. Replace the plugs (with new)and adjust the mixture. If you still have single cylinder misfires, identify them and fix the problems.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks moparmike and steve for your replies !!! I tried changing
all plugs and since it doesn't hold idle I wouldn't dare take it out.
This all started after I fixed the accumulator and left car at its
highest position .Could it be bad CO sensoe or dirty fuel ??? I
think it might be a bad sensor because I never could get the timing right no matter what I tried.Before (year ago) it would
start instantly !!! While it was parked something wrong .Any
pointers ??????

After checking what Steve recommends check your fuel supply particularly the fuel screen built into the fuel tank and the fuel filter. Of course your fuel tank would need to be emptied before removing the in tank screen. My vintage 126 380SE sat unused for a few years and developed an intermittent (after 10-15 minutes of operation) misfire and stalling problem when I put it back into service. Turned out the gas tank had corroded internally and would periodically clog the built-in gas tank screen. The intermittent nature was caused by the peculiar design of the fuel feed in the tank. Since the bottom of the tank is flat and couldn't locate the fuel pickup at any one low point in the tank, they installed a 6-8" tall plastic cup in the center of the floor of the tank and installed the fuel pickup in the cup. Of course the fuel would have to enter the cup from somewhere once the fuel level got below the top of the cup so MB (not content with placing a 1/2" hole in the bottom of the cup since the fuel could drain out on long, 130mph corners on the Autobahn or race track) installed a venturi device that would use the fuel returned from the fuel distributor to "suck" fuel into the cup. Only problem is that if the tank contained sediment (rust in my case), the sediment would be sucked into the cup, stirred up by the return fuel flow and would ultimately lead to plugging of the screen after X minutes of operation. Once the car sat for a few minutes, it would restart and run fine until the cycle would again repeat itself. You can get an indication of whether your tank is rusted by looking in the fuel filler neck and by removing the fuel level sending unit and peering inside. It goes without saying NOT to create sparks or use open flames and technically vaporproof flashlights or lights should be used to view the internal condition of the tank. Good luck.

Hi My 91 560 sel has the exact same problem that just developed in the last two months.. I have replaced the coil plugs wires cap rotor.. it idles a little rough at the moment still.. and when I give it gas it tries to go but eventually the power drops and I run the risk of stalling.. I give it power it bogs down and wants to stall.. I i let of the gas the revs come back up and the idle returns to mostly normal but again any attempt at acceleration leads to i mmdiate bog down and potential stalling.. update the ignitions system helped alot.. there was a time it would not even start..but thats taken care of.. Im thinking now its a fuel issue.. the pumps checked out ok.. the other components left are the fuel dist and/or the relay.. will replace the fuel relay/filter shortly and then the fuel distributor if those two dont do the trick...
good luck
Demeterial

Thanks demeterial ! ! !
I just finished pumping out fuel tank, it was full with water ! I will
mount back pumps and filter tomorrow put fuel from GOOD gas
station and then see how it fires. Its amazing that most off the
fuel didn't even smell like fuel !!! Pardon the pun but it smelled
watered down.Please let me know how you make out !!!

Thanks demeterial ! ! !
I just finished pumping out fuel tank, it was full with water ! I will
mount back pumps and filter tomorrow put fuel from GOOD gas
station and then see how it fires. Its amazing that most off the
fuel didn't even smell like fuel !!! Pardon the pun but it smelled
watered down.Please let me know how you make out !!!

hey how did you make out.. cured I hope I am treating my issue the same.. gonna get a new filter on their shortly and I think this will get me up and going

I'm waiting for parts to come ! They should arrive soon but I'm
going to take out tank and change the Fuel Screen, check for rust and debri and change the different seals and the Fuel Filter just to get the "could be tank!!!" out of the way. After that the only thing that could cause problem would be the Pumps but that's easy to change . Thanks and let me know about your progress !!!

hey guy I have sent my mercedes to the local mech.. I let him know what I had worked on and gave him instructions on what to do.. you see I live in Oklahoma bartlesville to be exact.. and techs are hard to come by.. I advised them to flush the fuel tank and I have an ovp relay coming and I was wondering if there is a flywheel position sensor on these cars I can not find any info regarding.. everything I have read regarding states that this may cause the running rough idle hard start problems I am having..
Thanks
D

hey hows it coming my girls is still parked.. waiting on parts too.. let me know how it goes.. I thinkwe can save each other alot of trouble/headache.. I have treated all electrical problems..with no real results Im very interested to find out your results
D

Believe it or not but I haven't started her since I put tank back in ! After
changing chain, rails and seals I took off timing cover to change remaining
2 rails . Now I'm waiting on gears because she "deserves" them . Did you set
timing correctly on yours ? I take it that you had filters changed when you took out tank ?! Does your car start up right away or it makes rasping/snorting
sounds ? Good Luck . . . !!!