Question about Mercedes-Benz 560-Series

4 Answers

I have a 560sel that is very hard to start when warm after sitting for a few minutes, the primary fuel pressure holds overnight, but I noticed that the fuel distributor was leaking fuel into the throttle body at rest so I replaced the fuel dist. with a rebuilt unit and it does the same thing, almost all the components have been replaced. Did I get a bad dist or could it be something else. The only way that the car will start warm is by holding the throttle to the floor while cranking for a long time (like it's flooded) and then when it starts it blows black smoke out the exhaust. any help will be appreciated.

Posted by on

  • 2 more comments 
  • willoughbydj Sep 19, 2008

    On my 560sel the only place I see fuel leaking is from the bottom of the fuel distributer, as far as I can tell coming from around the pin that the throttle plate depresses. Is this acceptable or can anything other than a faulty fuel dist cause this, because I've had the same symptom with the original and the replacement unit. I have also replaced all the fuel injectors, buckets and seals. I've replaced the fuel pumps, accumulator, pressure regulator, temp sensor, and like I said it holds pressure overnight. thanks for any help.

  • willoughbydj Sep 19, 2008

    The pressure on the car is 48psi at rest and 92psi while running, which seems to be within specs. I'm hezitant to replace the fuel dist. again since I' ve done it twice.. I bought the dist at performance automotive at a fraction of the price I found anywhere else, if this is my problem I'd appreciate any feedback before I call them again. thanks

  • willoughbydj Sep 19, 2008

    All of the injectors seals and buckets were just replaced, is fuel supposed to leak out of the bottom of the fuel dist? in approx 35 min all the fuel from accumulator is leaking into intake below flap. thanks for any help

  • willoughbydj Sep 19, 2008

    thanks for all the imput.

×

4 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Master
  • 1,586 Answers

The black smoke is a sign of running rich, so chances are your car is still leaking fuel into the throttle body and the startup is especially rich. The injector itself (at the throttle body) is a likely culprit - if the pintle is leaking, or the O-rings that seal the injector in its housing are cracked, worn, or split (which is likely -they're rubber and are on a hot metal engine), then it can allow fuel to leak down and cause the choking richness that your car is seeing at startup. I'd look into an injector and/or O-ring replacement to cure the problem.

Posted on Sep 19, 2008

  • Ed DITZLER
    Ed DITZLER Nov 03, 2013

    thanks Jeremy Dellow ,my name is Ed. i was just surfing around when i came across your solution for , runs rich. my 86 Benz 560 SL has this same fault.

  • Ed DITZLER
    Ed DITZLER Nov 03, 2013

    i will keep you posted on what iam finding,Iam a Range Rover tech in Fresno

×

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that got 5 achievements.

    Governor:

    An expert whose answer got voted for 20 times.

    Scholar:

    An expert who has written 20 answers of more than 400 characters.

  • Expert
  • 163 Answers

I think your replaced fuel dist is also faulty. It must be checked at a special work station to ensure it is ok and refit to try.
Good luck!

Posted on Sep 19, 2008

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Genius:

    An expert who has answered 1,000 questions.

  • Master
  • 1,665 Answers

Remove fuel injectors .They must be cleaned and checked. usually this is not DIY work unless you have special tools at your place.

Posted on Sep 19, 2008

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    President:

    An expert whose answer got voted for 500 times.

  • Master
  • 1,450 Answers

Is your fuel pressure in the range it should be? if it is too high it can cause this.if it is ok then it has to be a bad fuel dist or the seals that seal it.

Posted on Sep 19, 2008

  • 1 more comment 
  • TripleTauto
    TripleTauto Sep 19, 2008








    Fuel Distributor - Leakage Confirmation

    Notes








    91mercedes04
    REF. NO. MBNA 07.3/18





    TO:
    OUR MERCEDES-BENZ PASSENGER CAR DEALERS



    DATE:
    September 1991



    SUBJECT:
    ALL MODELS WITH CIS-E FUEL DISTRIBUTOR LEAKAGE


    We have received a number of warranty claims with the complaint of internally leaking fuel distributors. After extensive bench and in-vehicle testing of these fuel distributors, we have found that most of these parts are not defective.

    When testing a fuel distributor in a vehicle, the only way to confirm internal leakage is by performing the leak test as described in our service literature.

    A possible indication of an internally leaking fuel distributor is when the Lambda "On - Off" ratio readings at idle vs. 2500 rpm (1) cannot be brought within 10% of each other by adjusting the idle mixture adjusting screw.

    If performing a visual check, please keep in mind that when pressing down the airflow sensor plate the control plunger is lifted off the seal which prevents fuel from leaking. By doing so, some fuel is allowed to seep down the plunger to act as a "lubricant" between the plunger and the plunger barrel in order to keep the free movement of the plunger.

    Whenever the airflow sensor plate is pushed down and the plunger is lifted off its seal, it is normal for a slight seepage of fuel to be visible down into the intake. If the plate is held down long enough, a small puddle can form (note: with the fuel pumps shut off, the max. 2 cc content of the fuel accumulator can be pushed out).

    Refer to Service Microfiche job no. 07.3-120 for all testing procedures.




    Note:
    All warranty returned fuel distributors will be closely monitored. Non-defective parts will be returned to the dealer and the dealer's warranty reimbursement account debited.



    (1)
    With purge line disconnected and pluggedthis is a bulletin i found

  • TripleTauto
    TripleTauto Sep 19, 2008

    Are you sure the airflow plate is closing? if it is staying open some it will cause your problem

  • TripleTauto
    TripleTauto Sep 19, 2008

    if the air flow plate does not close or is misadjusted this will cause this problem

×

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

1992 F350-7.3 4wheel drive is hard to start after changing fuel filter and fuel pump. Why is it hard to start?


indicates fuel leak back and fuel pressure drop
check filter installation for seal not sitting properly, loose fuel line fitting , pump installed correctly (flow wise ), filter installed correctly (flow wise)
air getting in to fuel lines
the thing you are looking for is indicated by the initial hard start but when started runs ok ( good fuel to the engine eventually) and then by the fact that if the engine is allowed to sit for a long period the problem returns meaning that the fuel pressure is not being held
could even be a problem fuel pressure regulator allowing the fuel to bypass ( no pressure =hard starting) then gets enough pressure to run ok but allows that pressure to drain off over time

Oct 29, 2016 | 1992 Ford F350

1 Answer

I have a 1998 chevy 1500 with a 4.3 liter engine,after it sits overnight it takes a while to start. After it is warm it starts fine and runs good,it happens after its cooled down


I would start by checking fuel pressure via the schrader valve on the fuel line (near the rear of the intake manifold). The vortec engines needed considerably higher fuel pressure than most to start cold, and it is quite common for a weak fuel pump to cause a cold only no start condition with that engine. You should see around 50-60 psi with the key on / engine off for about 3 seconds. Also, if the pressure drops very quickly after a few seconds, the fuel pressure regulator could be to blame.

Oct 30, 2014 | Cars & Trucks

1 Answer

The diagnostic connector on my 1990 Geo Prizm is dirty. Does this effect anything. It is hard to start when cold or has been sitting for a few hours. When it does start it runs rough for a few minutes...


if it contines to run fine dont mess with however if it starts acting out again sound like possibly loss of fuel pressure have it check next with gauge on fuel system allow it to sit overnight and see what gauge reads in am BEFORE trying to start engine let me know if you need help

Mar 07, 2011 | Geo Prizm Cars & Trucks

1 Answer

I am having a problem with my car starting. It mainly happens when in the garage and when its been sitting overnight. It seems to good battery.It ALWAYS does start, but only after trying it 3-4 times after...


if still under warranty have dealer perform fuel rail residual pressure test.probably defect w/pressure regulator /check valve in fuel tank.fuel rail does not hold residual pressure so when you start after sitting for extended periods it takes time for pressure to build up and vehicle to start.

Jan 17, 2011 | Nissan Sentra Cars & Trucks

1 Answer

99 jeep cherokee with 4.0 straight six takes extra long to start


The request doesn't say what the problem is...takes extra time to start?

Sounds like fuel-related - injectors/fuel pump/fuel filter? Is there a strong fuel smell or black exhaust for a few seconds/minutes after starting it when it's sat overnight? If so, then you've got a leak causing excessive fuel...kind like 'flooding' the engine on old cars w/Carbs.

It could also be the temp. sensor. If it thinks the car is 'warm' it won't give the car enought fuel to start when cold.

GL,
Td

Jul 23, 2010 | 1999 Jeep Cherokee

1 Answer

My truck is hard to start after sitting for short periods. After sitting overnight, it's starts easy. Not sure if the problem is related, but the truck starts to idle rough after idling ofr a minute. Runs...


Your fuel pressure regulator is probably bad. It is on the fuel rail. With engine off pull off the vacuum line on the regulator and if fuel runs out then the regulator is bad.

Jul 01, 2010 | 2002 Chevrolet Silverado 2500HD

1 Answer

Hard starting of 95 accord lx


it could be your IAC valve

Sep 16, 2009 | 1993 Honda Accord

1 Answer

Cold starting problem


you could have a couple differnet issues. cold start misfires, an intake air leak, poor compression with engine cold,or a fuel pressure issue with a leaking injector or fuel pressure is bleeding back due to a faulty pressure regulator. my recommendation is to buy a fuel pressure gauge and monitor pressure overnight. you could also pull the fuel rail and see if an injector is leaking at the same time. you can spray the intake system with a highly volitile liquid(with engine running) to see if idle speed changes to check for an air leak

Apr 27, 2009 | 1999 BMW M3

2 Answers

Hard but eventual start


Sounds like you may have a leaky injector which is both leaking fuel into one of the cylinders, and bleeding down any fuel rail pressure. Extra fuel makes it hard to start, loss of rail pressure takes a few seconds for fuel pump to build pressure back up.

Jan 24, 2009 | 2001 Dodge Dakota

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

372 people viewed this question

Ask a Question

Usually answered in minutes!

Top Mercedes-Benz Experts

Colin Stickland
Colin Stickland

Level 3 Expert

21949 Answers

yadayada
yadayada

Level 3 Expert

61168 Answers

Michael Contreras
Michael Contreras

Level 2 Expert

164 Answers

Are you a Mercedes-Benz Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...