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MG Midget and Sprite Technical - Fuel overflow from float chamber

Hi,
Apologies if this is a daft question, but I dont know too much about the workings of the carburetors.
I had to remove the fuel tank from my frogeye. Whilst the system was "dry" I also replaced a small length of the fuel line near the carburettors - I have the original twin SU's.
When I started her up, I was upset to find a fairly large pool of petrol under the bonnet. But my new fuel line did look dry & OK. I am thinking that it overflowed from the rear fuel chamber, as there was definitely a drop of petrol at the end of the overflow pipe still.
But now, it doesn't seem to leak. The system has been dry for about 4 weeks, so could it be that the float jammed but has now released itself? -If so, is this normal or does it need investigation?
Many thanks
Graham M V

Could have been some cr*p in the tank had been disturbed and found its way down the line; then it spent a while preventing the valve in the float chamber closing before dropping to the bottom of the float chamber out of harm's way.

Quite a common occurrance when and old tank is disturbed; fix is to fit an in-line fuel filter ahead of the carb.

Frogs are simple cars... in a couple of years you'll know it inside out.

A
Anthony Cutler

X2 for the above. Had exactly same problem when recommisioning mine. In line filter sorted it out. Cheap as chips and a doddle to fit>

Mark
M Adams

X3 for dirt from the tank as the most likely cause. But I also note that it can happen for the needle valve to drop far enough and jam down with the plastic floats with the metal tang if they are worn and bodged in the past. Unusual but it can happen, so if a thorough clean and a filter doesn't fix it that's the next place to look.
Paul Walbran

Thanks. I have a filter, and renewed it at the same time. The tank is only a few years old. But as the tank was off for about four weeks, could it have been that the float initially just got wedged, and didn't float up?
Graham M V

Yes, it is possible. Shouldn't happen if everything is correct. Simple way to sort it for now is to remove the lid then replace it. The float and lever should be pushed right up into the working position as the lid is replaced (assuming the bowl is still full from its previous flooding bout). Long term you might want to investigate why full droop sllowed the valve to get out of line enough to jam open.
Paul Walbran

I believe that Paul has the correct answer. Often, the float lever drops far enough to trap the needle at an acute angel, jamming everything together so the float can't rise with the fuel level. This is only a problem when the fuel completely evaporates from the float bowl before the car is driven again. The fix for this is to cut some slots in the back of the lever to form a tab that will limit the drop of the lever. For instructions on how to correct this situation see the article, Float Lever Drop Adjustment in the Other Tech Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ Cheers - Dave
David DuBois

Thanks guys. I think you have the answer for me. It had certainly run dry for a few weeks, but after the initial misbehaving, I have had no leaks since.
Haven't taken the top of the float chamber off just yet as been pre-occuppied, and also thinking, if it ain't broke........

Thanks for the help, much appreciated
Graham M V

This thread was discussed between 03/05/2012 and 04/05/2012

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