w124 300CE 24V Fuel Relay Problem

Discussion in 'Engine' started by ninaandphil, Oct 30, 2011.

  1. ninaandphil

    ninaandphil New Member

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    Hi All,
    Help please... I'm very confused. My 300CE 24V M104, 91reg with a distributor cap.... There is no power to the fuel pumps and they are not charging when the ignition is turned on. So I assume the fuel pump relay is Kaput, which seems fairly common....
    Trouble is, despite reading lots of threads, I am at a loss as to which relay is the fuel pump one!
    I have taken out the relay behind the fuse box, part number 201 821 00 47, but see it advertised as a hazard relay on different sites, but it has pins 30 and 87 which are also described on here as shorting out the power to the pumps?? (Not tried due to doubts)...
    I also have the MAS relay from behind the battery, part number 011 545 82 32... another thread says that the MAS relay also controls the fuel pump on late M104 models.
    Can anyone tell me whether either of these two relays is the culprit..
    Thanks for the help in advance.
    Phil
     
  2. Druk

    Druk Administrator Staff Member

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    Behind the black cover behind the battery there should be a black box about the size of a fat fag packet with 'Kickdown' written on it. This is the FPR. iirc it should be to the left of the tall relay with the red fuse on top. If you find it, shorting 30 and 87 will make the pumps run continuous IF THE RELAY IS FAULTY.
    This will test the relay and will cause no harm short term.

    Edit. pins number 30 and 87 are common to many relays. The numbers designate power feed and supply pins.



    .
     
    Last edited: Oct 30, 2011
  3. grober

    grober MB Club Veteran

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  4. boomtings

    boomtings Hardcore MB Enthusiast

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  5. neilrr

    neilrr MB Club Veteran

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  6. OP
    OP
    ninaandphil

    ninaandphil New Member

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    Mercedes 300CE 24V
    Hi all..

    Thanks for the info.. I didn't mention mine is a manual, so no kickdown... but the 'fag packet' sized relay is there... looking more like it's the MAS relay though where the problem lies, but I would like a definitive answer for what the 'fag pkt' 20 851 00 47 relay behind the fuse box controls, hazard lights plus ??
    Also, the part number on my MAS relay is 011 545 82 32, different from any other I've seen...
    Any further info much appreciated.
    Phil
     
  7. OP
    OP
    ninaandphil

    ninaandphil New Member

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    Ahhh... now I've seen my MAS relay on neilrr's post and link above! Time to try and find a replacement!
     
  8. grober

    grober MB Club Veteran

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    2 things about these "MAS" relays which incorporate the FPR. One is they rarely go wrong and 2 they are difficult to source[ Inchcape http://www.mercedes-benz-parts.co.uk/ still list 011 545 82 32 on their site at £320-42!!!!]. Might be worth exploring the possibility of a solder repair to the original if that's the source of your problem but unlike the simpler FPR's its pretty unknown territory- might be a bit more solid state stuff in there?
     
    Last edited: Oct 31, 2011
  9. OP
    OP
    ninaandphil

    ninaandphil New Member

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    Update to problem MAS relay

    Hi all, a quick update.... I purchased a used MAS relay from Westminster auto spares on ebay... £40 including P&P. Plugged it in, car started first time! I tried shorting pins 1 & 2, as advised, before making a purchase, which did indeed start the fuel pumps up, confirming that this was the fault. Thanks to all who advised me.
    PS, will also post a pic on another thread of the shiny new charcoal filter, fitted and in place... thanks Grober, purchased from Inchcape using the part number you provided...
    Regards Phil...:thumb:
     
    2 people like this.
  10. trapperjohn

    trapperjohn MB Club Veteran

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    Thanks for the update Phil.
     

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