1989 500 SEC fuelling issue?

Discussion in 'Engine' started by Roygarth, Nov 9, 2013.

  1. Roygarth

    Roygarth Active Member

    Messages:
    99
    Joined:
    Aug 12, 2009
    Location:
    Norfolk
    Car:
    1983 W123 230E
    I have just bought an '89 500SEC. It has done very few miles over last 5 or 6 years and may have old fuel.

    If you floor it it accelerates perfectly well. But if you lightly accelerate it misses/wavers around etc.

    I'm hoping a tank of fresh fuel and a bottle of injector cleaner will sort it!

    Any ideas?

    Thanks
    Piers
     
  2. arfan786

    arfan786 Active Member

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    Dec 18, 2012
    Location:
    west midlands
    Car:
    mercedes benz 560 sec
    hi congrats on your new car.:thumb:

    If the car has been sat around for 5-6 years with old fuel in it my advice would be drain the tank of old fuel and then use fresh fuel and injector cleaner as otherwise you will have other gunk clogging up injectors etc.
     
  3. ianrandom

    ianrandom Active Member

    Messages:
    998
    Joined:
    Feb 19, 2010
    Location:
    Berks mainly, UK. Devon too a lot of the time.
    Car:
    1986 420SE, 1990 420SEC, 1989 2CV6.
    Hmm suddenly mine is doing the same.. Injector cleaner tomorrow I think.
     
  4. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    First thing is change of plugs, caps and rotor arm...Leads if they look old...

    People just dont change these basic items for some reason and they are the cause of most misfires on these.

    Fuel cleaner may help but I doubt it.
     
  5. ianrandom

    ianrandom Active Member

    Messages:
    998
    Joined:
    Feb 19, 2010
    Location:
    Berks mainly, UK. Devon too a lot of the time.
    Car:
    1986 420SE, 1990 420SEC, 1989 2CV6.
    New plugs today, the correct Bosch from MB. Rotor cap looks like new, cleaned the contacts anyway, same for the rotor itself. Leads are nearly new.
    Swapped the fuel pump relay and the injection computer, no change.
    Boo :-(

    Got a new filter but the old one is rusted on. Have to order the pipes either side before that gets changed.
    My thoughts are I've sucked up some gunk, I ran it out of petrol before about three times. It's been alright since but maybe that's what it is.
     
  6. WG M-B

    WG M-B Auhorised Forum Sponsor Authorised Forum Sponsor

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    Sounds like a spark problem. I would suspect the coil
     
  7. ianrandom

    ianrandom Active Member

    Messages:
    998
    Joined:
    Feb 19, 2010
    Location:
    Berks mainly, UK. Devon too a lot of the time.
    Car:
    1986 420SE, 1990 420SEC, 1989 2CV6.
    Thanks, I've been thinking of the coil too actually.
    Could it produce behaviour like mine and the thread owners?
     
  8. ianrandom

    ianrandom Active Member

    Messages:
    998
    Joined:
    Feb 19, 2010
    Location:
    Berks mainly, UK. Devon too a lot of the time.
    Car:
    1986 420SE, 1990 420SEC, 1989 2CV6.
    I changed the EHA today after reading via Google that an owner with exactly or symptoms fixed his car by having that changed.
    Thought it had worked, but nah. Admittedly it was off a non running spares car, but no difference.

    Roygarth, might work for you. It's only two screws, love repairs like that, lol.
     
  9. OP
    OP
    Roygarth

    Roygarth Active Member

    Messages:
    99
    Joined:
    Aug 12, 2009
    Location:
    Norfolk
    Car:
    1983 W123 230E
    Update!

    Car now accelerates and cruises fine but wanders/hunts badly when stationary. And often dies when you go from park into drive or reverse.

    Has had clean up of everything, new plugs, leads, fuel pumps.

    Any ideas?

    Thanks
    Piers
     
  10. John Jones Jr

    John Jones Jr MB Enthusiast

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    Location:
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    Mazda MX5 10AE, W201 2.5-16, W202 230K Sport man, Honda Accord & Suzuki 'Ricer'.
    There's several things I'd look at, like the Alternator regulator, OVP relay, Vacuum leaks etc. But first I'd get the mixture checked & adjusted. An hours labour charge with someone that knows KE-Jet would be well worth the expense. Cracking car BTW, enjoy.
     
  11. Dieselman

    Dieselman Banned

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    Check the insulator disk under the rotor arm. They can crack and allow HT voltage to short tot eh distributor body.
     

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