Fuel drip

Discussion in 'Mech Tech' started by iblaze, May 15, 2019.

  1. Hi all
    I have fuel drips from the bottom of both studs on the carburettor but it only does it when its warm weather I assume the fuel in the tank expands.
    Any ideas why?
    Also the battery is disconnected (dont know if that makes a difference)
    Also the carb has been stripped and all gaskets and new parts fitted. [​IMG]

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  2. That’s ^ the most likely cause of the problem. Why was the carb stripped?
    snotty likes this.
  3. You probably fitted dirt into the fuel metering needle valve, or fitted one that still had burrs from manufacture. Or put the plastic spacer in in the wrong order on the pivot.
    It does not bode well for the future. Its not petrol in the tank expanding as much as a simple leak.
  4. Likely the float chamber is overflowing, and that possibly fuel is finding its way out of worn throttle bushings. You need to make sure you’ve got the right thickness shim under the Solex float valve and that the new top gasket from the stripping kit isn’t twice as thick as it should be (which they are).
    Last edited: May 15, 2019
  5. There was gaskets missing looks like the PO had taken it apart then just reassembled it loosely to sell the bus ... the engine wasn't fitted it was in the back on a board the studs to the carburettor were only finger tight.

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  6. Has it got a gasket on the carb lid?
  7. I replaced bushes with these

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  8. Yes
    This is the kit I used
    The only part I didn't replace was the vacuum diaphragm as it didn't fit.[​IMG][​IMG][​IMG]

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  9. I’d send it back to JK if there’s no proper vac diaphragm. How thick was the top cover gasket?
  10. Same thickness as this one next to a 5p[​IMG][​IMG]

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  11. Whats it like the other way up ?
  12. There is meant to be a spacer gasket under the needle valve in the top of the carburettor fuel float chamber. I seem to remember its a copper washer.
    Leaving that washer/gasket out, the float valve will only shut with the fuel very high in the chamber as its on a lever where the float moves at least 5 times further than the needle. 1mm at the needle means the fuel is 5mm too high.
  13. To add to this, I had problems here. To check, turn the engine over so the pump activates and fills the float chamber. Carefully remove the top of the carb, but leave the float in, then measure the depth of the fuel surface from the top of the bowl. Quite tricky this as the meniscus on the fluid surface can mislead. I did it with the end gauge on my callipers but you could just use a piece of wire as a dipstick. The result should be 17-19mm, but there are various specs for this. Adjust with washers as needed.
  14. I decided to take it off to see if I could find any external leaks
    There wasn't any apart from the bottom was wet around the gasket.
    Something I did notice tho the back stud doesn't tighten up the thread that go6in the carb is stripped.
    Also the gasket has only the slightest indentation on it from the front stud being tightened but the back has nothing.
    I've found a bolt that fits so I'm going to see if it'll tighten up.
    I know this probably wont cure it but if it stops it leaking externally then that's half the battle.
    Just a thought too
    Since rebuilding the carburettor I've not set anything all I did was count the amount of turns on each screw and put them back to exactly that.
    She does start ok but there's a backfire pop
    Every now n then and when I take my foot of the accelerator she cuts out.
    I was going to attempt it using the carburettor sticky from the other day.
    But then I found the leak

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  15. Pull your dip stick and see if your oil smells of fuel
  16. No mate

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  17. Really you want to stop it leaking internally, as fuel will run down into the inlet manifold, and potentially into the cylinders.

    The kit top gasket you showed is about 2mm thick. This is far thicker than the original, and will jack the lid of the carb up by about 1.5mm. The fuel level in the Solex is set by shimming under the float valve with washers, but raising the "roof" will mean that the float valve operates at a higher level. I'd say either find a thinner gasket (or make one from 0.4mm stock), or put both supplied shim washers (0.5mm and 1mm) under the float valve. That may stop the float chamber overflowing.

    PS: having recently refurbed three of these things, I can confirm that most of the stuff in the rebuild kits is junk.
    wendygun, iblaze, Dubs and 1 other person like this.
  18. You're right about the gasket thickness so it's important to measure the fuel depth and adjust the valve accordingly. I'm awaiting some proper gasket paper as I wasn't impressed with the stuff in the kit I got sent and will make my own shortly.
    iblaze and paul2590 like this.
  19. Worth doing, and easy enough to make :thumbsup:

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