trigolf Posted July 4, 2023 Report Share Posted July 4, 2023 Last week I started work to replace a rear wheel bearing on my mk 2 Vit. So, rear end up on stands and springlifter in use etc. Recommenced work today and on entering garage a very strong smell of petrol! I checked the carb throats and fuel welling out of them which has polluted the very new front air filter Grr..! The fuel tank is almost full as I'd recently refilled it before deciding to change the rear wheel bearing. I have temporarily stopped the 'leak' by clamping the tank outlet hose( the boot is currently higher than the carbs). Am I missing something, as I would assume the carb needle valves would stop fuel flow, or is it gravity just overwhelming them? Link to comment Share on other sites More sharing options...
Nigel Clark Posted July 4, 2023 Report Share Posted July 4, 2023 The needle valves should stop fuel rising above the correct level in each carb's float chamber. Perhaps the front carb needle valve is letting by slightly, and the extreme conditions of the rear of the car raised high plus a full tank was too much for it. I would clean and check the needle valve as a precaution. Take off the new air filter and allow it to dry out then it should be fine to reuse. Nigel Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted July 4, 2023 Report Share Posted July 4, 2023 The needle valves should stop any fuel flow regardless of if it is pumped or gravity fed like when you go down a steep hill. This smacks of Uncle Pete's favourite little black slivers of rubber. Whip the float chambers off and check for contamination. If there is any then change your rubber fuel lines for new e.g. the Gates Barricade brand sold by the club shop. My Sixfire suffered from fuel weeing out of the carbs until I changed the fuel lines and fitted a glass chamber fuel filter between pump and carbs. Link to comment Share on other sites More sharing options...
trigolf Posted July 4, 2023 Author Report Share Posted July 4, 2023 22 minutes ago, Stratton Jimmer said: The needle valves should stop any fuel flow regardless of if it is pumped or gravity fed like when you go down a steep hill That's what I understand too. I changed all hoses to Gates last year and the carbs don't flood in normal use and I have'nt touched any of the connections since.🤔 Link to comment Share on other sites More sharing options...
johny Posted July 4, 2023 Report Share Posted July 4, 2023 The difference could be that when running any small leakage past needle valves is used by the engine but in your case with gravity feed even tiny leakage will eventually lead to overflow.... Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 5, 2023 Report Share Posted July 5, 2023 12 hours ago, johny said: The difference could be that when running any small leakage past needle valves is used by the engine but in your case with gravity feed even tiny leakage will eventually lead to overflow.... I agree, I reckon that it's just because the car was jacked up for a prolonged period and the fuel has seeped out. In normal running it won't happen unless you park facing downwards on a very steep hill... same as oil leaking from the front of the gearbox. Link to comment Share on other sites More sharing options...
johny Posted July 5, 2023 Report Share Posted July 5, 2023 yes shouldnt be a problem although I dont think the valves would fare well with the higher pressures that new fuel pumps often give these days so I hope the existing one has got lots of life left in it🤞 Link to comment Share on other sites More sharing options...
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