Electronic fuel cut off

Discussion in 'Mech Tech' started by Dicky5ash, Jan 20, 2019.

  1. Crud in the fuel won't help!
     
  2. I did have the sustainable tofu, so that’s ok.
     
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  3. And I thought he only went in search of Michelin stars


    Sent from my iPhone using Tapatalk
     
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  4. Only got to collect another hundred of them, and I get a toaster!
     
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  5. mikedjames

    mikedjames Supporter

    If the valve is sticking and you keep having problems then that totally points to dirt being your real problem.

    So the setup goes tank, metal fuel filter, solenoid valve, firewall , fuel pump , carbs.

    Filter first then the solenoid valve does not jam shut with dirt.


    My bus managed to catch fire while cranking for oil pressure once. Turned off the ignition which shut the solenoid valve, put out two small petrol fires with a single 1kg extinguisher, used battery quick releases to isolate melting wiring. Was back on the road the next day after an epic rewire across the top of the engine bay where all the wires had melted.
     
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  6. Thank you, much appreciated
     
  7. Chrisd

    Chrisd Supporter

    Following the two campervan fires recently, it reminded me to get one of these solenoids.
    Before I buy one I was wondering if the brass ones are better than the plastic and if they all work via the ignition rather than engine stopped but ignition on (crash) scenario?
    Cheers
     
  8. mikedjames

    mikedjames Supporter

    If the solenoid valve is wired with some relay / diode logic it can be made to open when cranking - diode from starter circuit powers relay, or made to open when the engine is running - diode from alternator D+ also powers relay that connects power to the solenoid valve.

    Either two diodes/one relay or two relays that both switch power to the solenoid.

    Personally I prefer a metal bodied valve , with metal braided fuel lines, then the fire will have more trouble burning through the walls of the fuel line or just melting the valve apart.
    Having plastic levers and insulation round the operating coil doesnt matter providing whatever melts fails with the valve closed...
     
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  9. 77 Westy

    77 Westy Supporter

    I bought a brass one (then read how hot it gets) and never fitted it but if I did it would be in the fuel pump relay circuit – if the engine stops so does the pump and the cut-off valve closes regardless of whether the ignition is on or not.
     
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  10. mikedjames

    mikedjames Supporter

    Obviously if you have a properly switched fuel pump, then the solenoid valve is powered a in parallel with it.
    And yes, the solenoid coil will get warm/hot. But it is cooled by the fuel flow through it, and air flow around it if its out on a chassis rail - its only about 2 watts of heat.

    You will never be able to set fire to the petrol or boil it with the heat from the solenoid alone. Maybe help it boil if your carburettors get too hot anyway.

    You never blinked when you installed that Carter rotary pump with the arcing commutator inside the petrol !! ...
     
  11. 77 Westy

    77 Westy Supporter

    I gave the arcing commutator inside the rotary pump some thought and realised in about a millisecond that there was nothing to worry about. And I gave the hot solenoid valve some thought too and know that’s not a problem. And one day I might even fit it, it’s one of these. https://tinleytech.co.uk/shop/lpg-p...-off-valve/petrol-shut-off-valve-high-output/

    I would not use the plastic valves or plastic fuel filters and especially not the glass filters that are prone to leakage and vulnerable to breakage that some recommend.
     
  12. Chrisd

    Chrisd Supporter

    Good point about flow rate as I'm planning to try to take my camper back to fuel injection in the winter and so would not want to restrict fuel. Shame the one you suggest does not have a bypass, but then again neither do either my fuel pumps (carb nor FI), so maybe it is not an issue.
     

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