How to depressurize the fuel system when removing fuel pump fuse does not work?

Discussion in 'General Motoring' started by martinxue, Feb 20, 2006.

  1. martinxue

    martinxue Guest

    Hi,

    I have a problem to depressurize the fuel system for my 1988 240GL
    sedan as I need to check the in-tank fuel pump. According to Haynes
    manual, I need to take off the fuel pump fuse and start the engine, let
    it stall and proceed to the rest of fuel system depressurization.

    But after I took out the fuses (even all the 16 fuses in the fuse
    panel), the engine still could not be stopped. I post the question a
    few days ago and from the information that I gathered, I suspect that
    someone has modified the electric wiring for the fuel pump, as this car
    was bought from someone else and it had been serviced by several
    mechanics.

    So are there any other ways to depressurize the fuel system?

    Any suggestions will be greatly appreicated.

    Thanks very much.

    Regards

    Martin
     
    martinxue, Feb 20, 2006
    #1
  2. martinxue

    M-gineering Guest

    1 somebody hotwired the relay: restore to factoryspecs, as the current
    situation isn't safe
    2 Ignore Haynes and unscrew a connection wearing goggles and with a rag
    wrapped around it.
    --
     
    M-gineering, Feb 20, 2006
    #2
  3. I was following the same advice for my 1999 V70 and probably stumbled over the
    same problem. The fix for me was to find the correct fuse. In V70 there is two
    sets of fuses: main and secondary - two locations - main is inside the engine
    compartment. In the main there is a fuel pump fuse.
     
    Peter Ziobrzynski, Feb 28, 2006
    #3
  4. martinxue

    Johan Plane Guest

    Hi,

    Sorry, but I can't see the problem. In my 265, there never was any pressure in the
    rear, i.e. the fuel lines to/from the tank. I just popped of the hoses and got the
    pump out of the tank. Came a trickle just as the hoses came off, bot that's all.
    Remember that the in-tank pump is just a pre-pump to the main pump located just in
    front of left rear wheel. It's after the main pump the pressure builds, but that
    pressure is contained from main pump and forward and doesn't kick back, and the
    return hose is pressureless - more or less anyway. When the main pump stops, the
    pressure drops quickly to nada..

    Johan
     
    Johan Plane, Mar 1, 2006
    #4
  5. How did we miss that? True - the lines at the tank have no pressure.
    Depressurization applies only to the fuel system between the main pump
    output and the engine.

    Mike
     
    Michael Pardee, Mar 1, 2006
    #5
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