[W126 Coupe] 1988 560 SEC loss of power

[shinzbox at aol.com]

 I had the exact same problem.
The culprit was the fuel cut-off and speed control relay. 
Jonathan knows the part number


 


Shin Takei
Professional Car Nut
Automotive Columnist
BEVERLY HILLS LIFESTYLE MAGAZINE
shin at BHLMAG.com
www.BHLMAG.com




 


 

-----Original Message-----
From: Dick Spellman <dick.spellman at gmail.com>
To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
Sent: Wed, Sep 23, 2009 5:25 pm
Subject: Re: [W126 Coupe] 1988 560 SEC loss of power












  

Russell,



Mine as well do the fuel filters where you don't mention when they were
last done and you may well have moved some debris from the tank.  I
should also mention that running the tank on less than full conditions
most of the time will create some condensation and corrosion in the
upper tank where no fuel resides.  It's just a good idea to do a fill
to prevent this condition.  Not an overfill, just fill to where the gas
pump clicks off.  Running on Premium will keep the engine in better
shape too.  You can add a can of BG-44K to the next fill to take care
of any build-up in the system and to clean the carbon off the piston
tops too.  Throw an Italian tune-up in after drinking a 1/2 tank of
fuel with BG-44K and that should do it. Having made these few
suggestions, I don't think your problem is related to running on a low
tank level.



How many miles on the SEC?



When did the O2 sensor last get replaced as it could create a l
ean
running condition if it's past it's life of 60k miles or so.



When did you last do the cap, rotor, plugs and leads?   Just so we know.



The fact that it's not quitting completely sounds like it is starved
for fuel but, could also be some component suffering from heat or age
and it's starting to go.

Perhaps the coil or the coil lead arcing which is why I ask about the
leads and so on. 



A question for this list...If the fuel pump relay fails does it fail
out completely or permit an interrupted run as Russell describes? 
Anyone?



Anyway, before throwing money at the car maybe get
these questions answered.  Wouldn't hurt to check fuel pressures and
fuel delivery volume too.



Dick



GreyGarageRuss at aol.com
wrote:


  
  
  
  

  
I follow this list daily and now have a
problem with my 1988 560 SEC which I could use some advice on.  Twice in the last two weeks while driving my car
lost power.  Each time the trips were at highway
speeds and after about 1-1/2 hours of driving.  On
each occasion, the fuel gage was close to the “R” (reserve tank )
level. The car lost most of its power (like running on 4 cylinders) but
did not stall.  I was able to get over to the
curb lane at about 15-20 mph.  I turned the
ignition off  each time, waited 4-5 minutes and
restarted….it then ran fine.

  
I have had two mechanics look at it but no
solution.  Both suggested fue
l supply problems
but the two fuel pumps were checked and appeared to be functioning
properly.  They also suggested a fuel sensor
problem but were unable to check sensor while problem was not happening.

  
Other suggestions included: blockage in
muffler system or catalytic converter!

  
Any advice would be appreciated.

  
Russell

  

  
  



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