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  #1  
Old 07-26-2015, 08:08 PM
Ron59b
 
Join Date: Aug 2007
Location: Richmond, Virginia
Posts: 485
1990 Mercedes 560 SEL Fuel Distributor Sticking?

Good evening all

I have a 1990 Mercedes 560 SEL with 220,000 miles. When I purchased the can, it had sat for a long period without being used or started. I purchased the car and lost my job, so it sat for about two years.

Now I have it being worked on by a friend. One of the last issues is the fuel Distributor Sticking and causing the car to idle rough or cut off. This happens when the car comes to a stop. When it cuts off, sometimes it is hard to restart.

My question is how to clean the fuel Distributor? I have seafoam in the fuel tank, and a fresh full tank of preimum gas. I am also wondering if a rebuild is a diy project?

I thank anyone who responds for your help.

Thanks

Ron

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  #2  
Old 07-27-2015, 06:51 AM
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Nothing short of replacing it with a known good one (not thought good), or a rebuilt one will solve your problem.

There are rebuild kits out there, but if your current distributor is showning any wear on the bores or the pintles, your toast.

It's a good chance your injectors are bad as well.

Jim
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  #3  
Old 07-27-2015, 08:47 AM
Ron59b
 
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Thanks Jim for the information.
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  #4  
Old 07-27-2015, 09:05 AM
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Trevor Hadlington
 
Join Date: May 2014
Location: Worcestershire in England
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Afew things can be done .Look in to youtube videos for fuel distributor clean . Means spliting it open and cleaning the valve. Will your car have a potentiometer on the side of the throttle body .If so it wears out ,as the carbon tracking piece inside..wears out as the lever travels across it . That to will be on the tube.. The throttle body can be the problem but not an easy fix it as to be re built . Inside it as this steper motor that opens and closes the throttle flap..
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  #5  
Old 07-27-2015, 10:02 AM
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ron59b:

If you would be so good, let us know what steps have already been taken to revive the engine. Compression readings? What, if any, ignition components have been examined and/or replaced? What lead to the diagnosis of "sticking"?

There may very well be some stickiness of the metering plunger, however, a number of other things must be confirmed to be right before addressing the fuel distributor (FD).

FYI, there are no pintles in the FD, no potentiometer on the throttle body, and no stepper motor.
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  #6  
Old 07-27-2015, 11:32 AM
Ron59b
 
Join Date: Aug 2007
Location: Richmond, Virginia
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The car had some starting issues. The fuel pumps, rotor button, plugs, fuel pump relay, overvtage protection relay, throttle body cleaned, and a lot of general cleaning of the fuel system. The cat converters changed. The car now runs smoothly but with a slight missing.

The guy that is doing my work mentioned that when coming to a stop, the car will idle down and sometimes cut off.he also mentioned that when it is not running properly, he can tap on the fuel distributor and it changes how it is running

He also mentioned that when cracking open the fuel lines at the fuel distributor, that on three of the lines there was no change in the idling. I hope this info helps.

Ron
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Old 07-27-2015, 12:55 PM
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Quote:
Originally Posted by ron59b View Post
The car had some starting issues. The fuel pumps, rotor button, plugs, fuel pump relay, overvtage protection relay, throttle body cleaned, and a lot of general cleaning of the fuel system. The cat converters changed. The car now runs smoothly but with a slight missing.

The guy that is doing my work mentioned that when coming to a stop, the car will idle down and sometimes cut off.he also mentioned that when it is not running properly, he can tap on the fuel distributor and it changes how it is running

He also mentioned that when cracking open the fuel lines at the fuel distributor, that on three of the lines there was no change in the idling. I hope this info helps.

Ron
Re: Slight missing
Has the compression been checked? A leakdown test performed?

Re: Tap on FD
Once the exhaust temperature, and the O2 sensor are up to operating temp, a mixture feedback loop becomes operative. The operating device at the FD is called the Electro-Hydraulic Actuator (EHA), and is located on the left rear corner of the FD. That may be changing with tapping. Or the metering piston itself could be sticking at the idle position. As a check on the metering piston, slightly depress the airflow sensor plate with the engine idling. If the roughness/missing diminishes, the initial position of the piston, or the nozzle check valves (see below) may be at fault.

Re: Cracking fuel lines
If it is the individual lines to the injection nozzles that are being opened, that points to sticky or dirty check valves in the nozzles. Once off idle, the fuel pressure and flow at the nozzles is high enough to keep the check valves open.
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  #8  
Old 07-27-2015, 02:19 PM
Ron59b
 
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Thank you, I will forward this to my guy to check.
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  #9  
Old 07-27-2015, 06:53 PM
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Quote:
Originally Posted by ron59b View Post

He also mentioned that when cracking open the fuel lines at the fuel distributor, that on three of the lines there was no change in the idling. I hope this info helps.

Ron
This suggests that those three cylinders are not getting fuel. This is what happened on my 560SEL. The distributor did not pass fuel to those cylinders.

I checked compression, replaced spark plugs, wires, cap and rotor chasing this problem. Dumped a bunch of Chevron Techron and Sea Foam into the fuel system. Even swapped out the injectors with a spare set.

Tried the rebuild kit for the distributor, but there were some microfine wear areas in certain areas of the distributor.

Got a known good distributor and was now getting good gas flow to all the cylinders. Still a bit rough, so new injectors were ordered. Now runs like it used to...smmooooooth.

The 560 had 241K miles on it when I did all this work. I had bought it back from the gent I sold it to years ago after a very minor rear end shunt that totaled the car. Knowing the care and expense lavished on the car since new, I couldn't let it go for scrap. Something morally wrong.... bad karma.

The car sat for bout 8 months and when I pulled it out of the shed, I had the driveability problems. I guess at these high mileages, stuff finally wears out.......

Jim
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94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles
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  #10  
Old 07-27-2015, 07:08 PM
Ron59b
 
Join Date: Aug 2007
Location: Richmond, Virginia
Posts: 485
Wow, thank you for the valuable information. I am in the process of looking for someone that rebuilds gas injectors. I previously found a great guy that rebuilt deisel injectors. He did a set fro my 300 SDL.

Thanks again
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Last edited by ron59b; 07-27-2015 at 09:32 PM.
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  #11  
Old 11-06-2015, 03:58 PM
Ron59b
 
Join Date: Aug 2007
Location: Richmond, Virginia
Posts: 485
Here is an update and a question:

Replaced the fuel distributor and hot wired the cold start valve. When the engine is started, and the air filter housing in not on the car, the engine idles steady but produces black smoke. When the air filter housing is on the car, the engine will not idle smoothly with acceleration. Either way there is black smoke. I believe the black smoke means the fuel mixture is too rich?

Can anyone suggest what to check next?
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  #12  
Old 11-06-2015, 04:43 PM
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Why is the CSV hot wired?
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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
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  #13  
Old 11-06-2015, 06:03 PM
Ron59b
 
Join Date: Aug 2007
Location: Richmond, Virginia
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Because the fuel relay, OVP relay, fuel pumps, and several other items were replaced, and still no power to the CSV. Couldn't fiqure out how else to power it.
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  #14  
Old 11-06-2015, 06:07 PM
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Try the ECU, been there before. Car was nearly impossible to start cold with a dead ECU and no CSV.

CSV is not designed to run 100%. It comes on at a certain temp, probably under 40*C, for a few seconds.

Also, you need a 560 ECU. It makes a difference.

Has the intake plenum and such been resealed yet?
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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
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  #15  
Old 11-06-2015, 06:38 PM
Ron59b
 
Join Date: Aug 2007
Location: Richmond, Virginia
Posts: 485
I have a spare ecu off of a 560 that I'll try. Can you explain the resealing of the intake pelnum? Adjusting the pelnum up or down doesn't remove the missing.

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Last edited by ron59b; 11-07-2015 at 06:41 AM.
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