Leaking fuel from rear carb

Fuel tanks, fuel pumps, carburetors etc.
JCS
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Joined: Mon Feb 04, 2019 6:47 pm
Location: CAMBRIDGESHIRE UK
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Re: Leaking fuel from rear carb

Post by JCS »

Jim

Sorry for the delayed posting.

Your image appears to show fuel leakage from the rear carburetter diaphragm, you have almost cornered the location by eliminating the float chamber yourself.

Both carburetters will need rebuilding. If you leave the front carburetter diaphragm, without renewing, you are likely to have problems with setting the fuel mixture as that front diaphragm will be hard and inflexible.

Unfortunately, the rebuilding of the front carburetter will require removal of the fuel supply bridge for the automatic choke. The banjo fixtures holding this supply bridge will likely be seized in place, if that is the case think ahead, just in case, and locate a new bridge piece before attempting dis-assembly.

Should the fixings be seized, warm up the assembly to just short of 90 c for 30 minutes, let it cool and then put it in a freezer at a very low temperature, say -25 c for about 4 hours and then immediately submerge it in citric acid. It might seem a drastic long-winded process but worth it if you can extract the banjos without damage. Failing that method obtain new banjo’s and have a machine shop mill the top and insides off the old banjos. Hopefully you will be very aware how easily these fittings break on these assemblies.

If you heat or cool these parts ensure that the complete dashpot, piston and needle assemblies are removed beforehand to prevent distortion.

Only fit anti-sink floats, spring loaded float chamber valves, and stainless steel throttle shafts if these are needed and available.
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