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  1. #1
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    Default Fuel Pressure gauge : Install

    Had a few hours in the garage this afternoon to get a few jobs done, including fitting the fuel pressure sender and wiring it into the gauge.

    All the extra bits and pieces were bought from Demon tweeks in the UK.

    Adaptor to break into the existing fuel line:


    Sender unit in place, sealed with Teflon tape:


    This is where the adaptor needs to fit in:


    Luckily I've got a separate switch on the fuel pump power line so I can isolate the pump and then turn the engine over to remove all the pressure from the fuel line.
    With all the pressure out, I removed the fuel line from the regulator and added a new piece of fuel hose to this side of things:


    Then its just a case of putting the adaptor in place and wiring the sender unit in. This involves one of my least favorite jobs. Running wires through the bulkhead!! I've already some extra wires and water hose for the waterspray kit running through there so its quite tight:


    And the Alfa wiring on the inside doesn't help:


    All went fairly well and this is what it looks like in place:


    Back to the interior, here are the gauges, firstly when everything is off:


    And switched on:


    All in all not to bad, but I'm not happy with the location of the sender or the quality of the electrical connectors under the bonnet. A couple of things to look at in the future.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

  2. #2
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    Nice job!

    Is there any difference if you wired ground via cable direct to the gauge or wired to the closer place under the bonnet?
    No replacement for displacement!

  3. #3
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    Default

    I've not tried that yet. I'm going to rig up a short earth strap to ground the sender under the bonnet and take some measurements.

    At the moment the gauge reads 2.4bar with the engine off and 2 bar with the engine idling.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

  4. #4
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    hmm...

    Should't 2.6 - 2.7 bar on idle?

    Over 2000 rpm should be about 3 bar?
    No replacement for displacement!

  5. #5
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    Default

    I'm not sure what all the figures should be, but the workshop method of measuring fuel pressure is done with the ignition on BUT the engine not running.
    The figures for that measurement should be 2.5 Bar.

    I would have thought that any rise in fuel pressure would be a function of inlet pressure rather than rpm.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

  6. #6
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    yes, its a function of manifold pressure - the reg is connected to the manifold pressure source. just set the fuel pressure to 2.5 bar static - ignition on, engine off.

    jim.

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