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Discussion Starter #21
Ok - would not even cold start this morning - just cranks.

I did check the crank position sensor and all looked good. I double checked the all the valves going to the fuel distributor since we had to remove a couple of them to get the gasket off and they were all tight.

At a loss now.
 

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Discussion Starter #22
Some additional information:
When changing valve cover gasket we also had to remove two fuel lines that were above it, one leading to the fuel pressure regulator and one into the fuel distributor. Could that possibly have caused and issues.
 

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1998 ML320, 1975 280C
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Only if you mixed them up when re-installing. You may want to just loosen one fuel pipe between the distributor and injector, have someone crank the engine and look for fuel leaking at the loose connection. If you don't have a fuel pressure test gauge, that will at least tell you fuel is going to the engine.
My guess is something with the electrical, though.
 

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Discussion Starter #24
Yet more information to chew on:
  • Turned key to run position and confirmed buzzing noise from fuel pump
  • Cycled key 3 times to run position and attempted to start and it quickly started with no throttle inpu
  • Idled smoothly and revved up to 3000RPM with no trouble in Park (did not try to drive it yet)
  • Noticed what looks like fuel leaks on the ground (from earlier) near fuel pump/filter/acc but no visually apparent leaks while running
Certainly now seems like a fuel issue - agree?
 

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Discussion Starter #26
The fuel filter was replaced on 9/9/2019 (and only 600 driving miles ago) do you think it's possible that it would be clogged that quickly?
 

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Discussion Starter #27
Latest update:
  • Car consistently starts without throttle when leaving the key in the run position for 10-15 seconds before cranking
  • Still stalls outside of idle in Drive, but as soon as we give it gas it sputters and dies
  • However, with the air filter off it could take a little bit of gas before stalling (still sputtered initially)
Seems like lack of fuel/lean? Thoughts?
 

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Discussion Starter #28
OK - one additional strange bit of information:
- with the air filter off, pressing on the throttle plate we can hear a light hissing noise (sounds like a vacuum leak) from the area around the fuel pump/filters (we are sure the noise is from there by laying under the car and confirming it). Any thoughts to what that could possibly be?
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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These engines don't have a distributor. It's coil on plug. If you are replacing the coils, that will cover the "wires" as well. With that kind of mileage though, don't be surprised if new plugs doesn't fix it for long. Those engines are known to burn lots of oil past the piston rings.
You have no idea what you are talking about. I can provide visual evidence if you wish.
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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These engines don't have a distributor. It's coil on plug. If you are replacing the coils, that will cover the "wires" as well. With that kind of mileage though, don't be surprised if new plugs doesn't fix it for long. Those engines are known to burn lots of oil past the piston rings.
LOL.
Try to pay attention to the forum that you post in.
 

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1998 ML320, 1975 280C
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The fuel tank has a vacuum system as part of the EPA systems in the car. That MAY be part of the sound, but I don't think so. I would look again at the fuel pump and filter. Also check the tank, as in the fuel pickup. There is a screen inside the tank that stops all the large debris from entering the filter/pump. If it's plugged you will have problems.
 

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Discussion Starter #33
New update: now won't start at all even after cycling key to run position multiple times and quite a bit of cranking.

Help!
 

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Is the fuel pump working? You may need to check fuel pressure/ delivery after the pump. If there's adequate fuel, then the issue must be spark. Whether the issue is fuel or spark, there's a multitude of things that may be at fault for each, but need to eliminate one at a time
 

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1986 560 SL
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I offer nothing to help the problem at hand, but this thread is further proof that old cars are often susceptible to multiple unconnected faults. Here an ignition issue has devolved into a fuel issue, defying logical diagnosis. Frustrating!
 

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I offer nothing to help the problem at hand, but this thread is further proof that old cars are often susceptible to multiple unconnected faults. Here an ignition issue has devolved into a fuel issue, defying logical diagnosis. Frustrating!
It is simply a way of diagnosing the problem. The rough idle may not have been an ignition problem from the start, or it may totally have been an ignition problem, so considering the fuel system is logical. The fuel delivery system is relatively easy to check and eliminate as the cause, and is a good place to start since the original ignition components have been since re-installed and an issue still exists.
In my experience, faults in older cars are easier to diagnose than newer models. It becomes a little harder in a forum when most people are just trying to help without actually seeing the car.
 

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1982 MB 380SE 1999 S500
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trying to locate a picture of an EHD valve and can't seem to find one - where is it located?
Not to familiar with 560 engine but sounds like the vacuum advance is not working. You mention a loose hose. Check it for leaks/defects etc and vacuum.
 

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300sel W109, 280S 70 , 220s 62. 230 66. Lancia Flavia 63.Pininfarina
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Seems a few spark plug wires are still mis-installed as you mention the telltale 'backfire' Symptom which occurrs when a few leads are in wrong cylinders . Recheck afresh .
Blackbox attached to side of fuel distributer is 'EHA ' unit. -Electro hydraulic actuatuer - .
 

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1988
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I had a similar problem. Turned out to be a clogged up fuel filter in the gas tank. I replaced both the in tank and outer filter. No more stall in drive.
 

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I'm one usually looking for help so I feel rather out of sorts to try to offer help. I suggest the Encycclopedia Germanica in the above sticky. Scroll down quite a bit to section 07.3 where you will find KE Jet explanation. This is very informative including a lot of tests using just a multimeter. It also includes a legend to use duty cycle testing. I would do this to see if it points you to anything.

Fortunately you have not attempted to adjust the Air/Fuel meter. This is not a fuel mixture adjustment and there is much for you to do before you mess with it. I know this from lots of research on this forum.

Your problem does sound fuel related. Stalling under load sounds like fuel starvation to me. I would suggest getting a fuel pressure test kit. You can rent them from most part stores like O'Reilly, AutoZone etc. Hope this helps.
 
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