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How to lest fuel pressure

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Karl W, Nov 8, 2012.

  1. Karl W

    Karl W Active Member

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    Joined:
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    Location:
    Wakefield
    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    Hi,



    I don't have a fuel pressure testing guage and neither does the local garage, Is it possible to read the fuel pressure through the 16 pin diagnostic port. I can fault code read the system using a power scope.



    My local garage has various old testing equipment and they are sure they'll have something that works but they and me don't know what pins to connect to on the diagonstic port to find what the fuel pressure is at the injectors.



    The car is a 95 e200 W124, thanks for reading.
     
  2. Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    No, the only way is with a gauge connected to the pressure test port on the fuel rail.

    If I may ask, why check it?
     
  3. OP
    Karl W

    Karl W Active Member

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    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    The mixture is running lean when warm, so I want to check the fuel pressure at the rail before working back to the pumps. When you spray some engine start spray in the air intake it sorts the problem.
     
  4. Alex Crow

    Alex Crow Senior Member

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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    What are lambda values doing?
    Any fault codes to go with?
     
  5. OP
    Karl W

    Karl W Active Member

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    Joined:
    Jul 4, 2010
    Location:
    Wakefield
    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    It's always been error free, I just get the blink from the light that denotes no error codes. I've just replaced the Lambda sensor the previous sensor was warnout and was the orginal item so changed it for another OE sensor from the dealer. Tickover it fine warmed up give it some gas and it's going lean. It would be handy if I could see what was happening on the road you don't have to go far before it's popping n banging
     
  6. mattkh

    mattkh Senior Member

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    Your Mercedes:
    W168 1999 1.6
    Hi
    Another way would be to replace the fuel filter and see if it runs better.
    How old is the fuel in the tank ?
     
  7. cleverdicky

    cleverdicky Senior Member

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  8. Alex Crow

    Alex Crow Senior Member

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    Joined:
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    Location:
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    Your Mercedes:
    W169, W124, w202, W203, KTM 250 EXC, VW T25 camper and a Polo in a pear tree
    How can you be sure it is lean, what is the lambda voltage doing?
     
  9. OP
    Karl W

    Karl W Active Member

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    Joined:
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    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    Hi, I ran the volt meter over the sensors and voltage and ristance os fine. When I fire it up it will start fine from cold and after giving it some revs it starts to pop annd bang. If I spray some fuel into the air intake and rev it no problems. Thanks what making me think it's running lean
     

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