fuel pump and cut off switch

Discussion in 'Mech Tech' started by wendygun, Jun 26, 2017.

  1. I am having to use an electric fuel pump as my re-built engine is using a fuel injection case from a beetle and I will be using a fuel cut off switch as well 162394786041_1.jpg just a live cable and earthed by the body mount.
    looking at this diagram pump.png
    would it be best to take the same live '87' straight to the cut off or does anyone have a better way.
    any ideas of what size wire would be needed.
    I did try and find a thread that zedders put up ages ago but I don't know if its been removed when he left for the other side....
    engines ready to go back in 'YAAAY' so this job is next to do before along with new fuel lines even though the ones fitted don't look that bad but are only r9 so looking for full ethanol resistant this time. belt and braces.....
     
    Valveandy likes this.
  2. ron

    ron

    my fuel pump runs off a relay switched on by the ignition switch , what i,ve done is run the earth wire from the relay up to a switch behind the drivers seat - the pump can then be isolated remotely and it also acts as a security switch
     
    Gingerbus and wendygun like this.
  3. I have both the fuel pump and the solenoid running from the same feed from the relay. Just one relay. both are switched from the oil pressure warning feed.
     
  4. was it a 4 pin or 5 pin relay......
     
  5. You can do it a number of ways.
    The best is to use a tachometric relay, simple wiring although the most expensive.
    [​IMG]

    Or by the oil pressure switch, and a changeover relay, has the advantage the relay is not energized to power the pump it only energises without oil pressure to switch the pump off.
    [​IMG]

    Or by the generator but has the disadvantage that the pump will stop immediately if the fan belt breaks or the generator stops working.
    [​IMG]

    Wiring depends on the type of pump but if it is a Facet then they only draw a couple of amps.
     
    Last edited: Jun 27, 2017
  6. Just looking at this does the amps have any effect on the relay the h version is 30amps as opposed to a gti relay of 17a
     
  7. mikedjames

    mikedjames Supporter

    The rated current of a relay is a do not exceed value. Less current is OK like 3 amps in a 30 amp relay .
    .. ( until you get to very tiny currents when big contacts have too low mechanical pressure and the current isnt enough to melt a spot in the contact to make a good connection.. microamps )
     

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