Help! Fuel!

Discussion in 'Mech Tech' started by RM92, Sep 15, 2019.

  1. So just got back from a run, heard a sucking noise like a vaccume or sucking noise of liquid somewhere in the engine bay near the left carb, then a drip fell from the carb, petrol... actual fuel lines are all bone dry. But carb body is wet with fuel.

    Any ideas as why??? Luckily a problem has arose just as I’ve pulled up... as the drippings stopped for now.

    Twin Webber carb setup

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  2. Needle valve dribble through wear and / or heat soak boiling petrol .

    Thick heat insulated gaskets under the carbs. New needle valves.
    Gooders and Dubs like this.
  3. Sorry don’t quite understand the first bit?!

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    Gasburner44 likes this.
  4. If you have twin Weber ICT carbs it could be the float needle valve worn & sticking causing fuel to overflow and drip into the manifold.
    The heat soak is the carbs getting too hot due to heat transfer from the engine. When you turn off the engine after a run the temperature goes up for a while due to no air flow. This transfers to the carbs & boils the fuel again causing it to spill into the manifold.
    Thick insulating carb to manifold gaskets help prevent this happening. Eurocarb sell them.
    What fuel pressure do you have? Too high pressure will wear out the needle valves quickly.
  5. Brill thanks will look into that, fuel pressure... how’s it measured?

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  6. You can buy a T piece that fits into the fuel line and a small gauge that screw into the T. Eurocarb have them, but I imagine other places will do too.
  7. what fuel pump do you have? if it was originally a fuel injected engine (my 78 was) and you're running the webers with this pump then don't bother measuring the pressure - it'll be too high. Either fit low pressure pump or a pressure regulator (and renew the needle valves)
  8. Merlin Cat

    Merlin Cat Moderator

    Sorry @RM92 I’m jumping on your thread.

    How can you tell if your pump is high or low pressure please? Mine was Fi but is now twin carbs.
    rob.e likes this.
  9. Show us a piccy, Alex, someone may recognise the make or pump model and know if it's low or high pressure.
    Merlin Cat likes this.
  10. @RM92 I'll take a piccy of my fuel pressure gauge for you and post it here.
  11. Merlin Cat

    Merlin Cat Moderator

    Ta. Good job I’ve been to Techenders so I can recognise the fuel pump (maybe) :). I will photo all the engine bay!
  12. Just the standard mechanical one?

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  13. It’s been fine for the last 5 years, carbs untouched so can only assume somethings sticking causing an overflow?

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  14. If it's not been changed, then @rob.e has hit the nail on the head. Sorry, to be the bearer of bad news, but type4 pumps are so much fun to remove..... :(
  15. Mine had a mechanical pump. The pressure is still too high and wears the float valves over time. I swapped mine when I replaced the float valves for a Huco electric pump, again from Eurocarb.
    Take a look at Wayoutwestie website he is very knowledgeable about Weber ICT carbs.
    mgbman and paulcalf like this.
  16. Here's my fuel pressure gauge.
  17. I haven’t got a type 4 engine it’s type 1

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    paulcalf likes this.
  18. Do you have the twin Weber ICT carbs fitted?
  19. I do yes

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  20. Ok, so type 1 fuel injection?

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