560SEL Fuel System Problem
02-08-2017, 10:44 PM
#1
Member
Thread Starter
560SEL Fuel System Problem
So a friend of mine and I recently bought a 560SEL for very cheap, it has an interesting issue.
It idles VERY VERY rough at around 400 RPM, kind of stumbles, and dies occasionally
It will not rev above 1500 RPM at all on gas.
It will rev perfectly fine if you try while spraying gas/starter fluid into the air sensor.
Pressing the gas while its idling causes it to stall out.
Pressing the air plate down very slightly causes the idle to increase to ~800 and become perfectly smooth but only while the plate is held down.
The fuel economy gauge also doesn't work, but that might just be because this gets 15mpg.
The previous owner replaced the fuel pumps without success.
Also, it has gained only 4k miles since 2003, so Im guessing it hasnt traveled under its own power in about a decade.
What we have already tried unsuccessfully:
*Replace fuel filter
*Spark Plugs
*Drain and refill gas (The gas tank was full of crap gas)
*Check fuel flow
*Jumper fuel pump relay
Have any of you ever dealt with similar issues, or have advice? Also, the ABS light is on but I do not believe its related.
EDIT: It behaves EXACTLY like this video:
It idles VERY VERY rough at around 400 RPM, kind of stumbles, and dies occasionally
It will not rev above 1500 RPM at all on gas.
It will rev perfectly fine if you try while spraying gas/starter fluid into the air sensor.
Pressing the gas while its idling causes it to stall out.
Pressing the air plate down very slightly causes the idle to increase to ~800 and become perfectly smooth but only while the plate is held down.
The fuel economy gauge also doesn't work, but that might just be because this gets 15mpg.
The previous owner replaced the fuel pumps without success.
Also, it has gained only 4k miles since 2003, so Im guessing it hasnt traveled under its own power in about a decade.
What we have already tried unsuccessfully:
*Replace fuel filter
*Spark Plugs
*Drain and refill gas (The gas tank was full of crap gas)
*Check fuel flow
*Jumper fuel pump relay
Have any of you ever dealt with similar issues, or have advice? Also, the ABS light is on but I do not believe its related.
EDIT: It behaves EXACTLY like this video:
Last edited by m00nsh0t; 02-08-2017 at 11:34 PM.
02-09-2017, 08:45 AM
#2
Out Of Control!!
You need a pulse counter to determine the faults---if you are not familiar with the diagnostic tool for older MB's, do a search and study hard as the older MB's require a god understanding of he cars systems
02-11-2017, 11:54 PM
#4
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Join Date: Apr 2010
Location: Woodinville, WA
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1989 560 SEC -Supercharged
Take off the airfilter and clean/lube "All" the throttle linkages. I have found a couple of these neglected w126's that had the same symptoms. When you open the throttle from the firewall area all the levers etc. should open and close in a smooth manner. Look and lube everything you see that moves from the rear to the front of the top of the engine.
02-14-2017, 11:17 PM
#5
Member
Thread Starter
Its not a vacuum leak, and its not the throttle linkages.
I replaced the EZL and ignition coil bc the last ones were definitely bad and that made it a bit better but did not get rid of the issue.
Also, its putting out white smoke that does not smell like coolant at all, and not in a high enough quantity to make me think head gasket. Also no combustion smell in overflow tank or signs of gasses in water.
Using the pulse meter I am getting a voltage supply iswsue on circuit 15r.
I replaced the EZL and ignition coil bc the last ones were definitely bad and that made it a bit better but did not get rid of the issue.
Also, its putting out white smoke that does not smell like coolant at all, and not in a high enough quantity to make me think head gasket. Also no combustion smell in overflow tank or signs of gasses in water.
Using the pulse meter I am getting a voltage supply iswsue on circuit 15r.
