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Carb overflow

Carb Overflow

To all,
If it wasn't already obvious, I'm about to illustrate my ignorance of carb
operation, especially SUs. I was always taught that "carburettor" was a
French word meaning "leave it alone." Despite this admonition, I've
apparently got to dig into one (or both). Right after I filled up my tank
the last time it started running roughly and the idle dropped off
substantially. When I had time to investigate I found most of the fuel
going to the rear carb was coming in and immediately going out the
overflow. Is this a float problem? - Thanks, Jim Voorhies XK140 FHC White
Bluff, TN

It is most probably a float problem. Undo the top of the offending
carburettor bowl. You will probably find the float stuck at the bottom.
Sometimes all that is needed is to unstick it. If it sinks back to the
bottom after you unstick it then it has a hole in it which must be patched.
- Dave and Linda Freeman

Jim, I keep a large paper clip in the car tool roll that I straitened out
then bent a little leg on the very end. ________________________I  like the
drawing I just made (didn't come out here - Ed.). The floats are sometimes hard to get out unless you
turn the car upside down. Anyway,  Just stick the bent end strait down
between the float and the wall of the bowl. Turn it so the leg goes under
the float and lift it out. Have a rag ready, dry it off and then shake it a
little to see if there is gas inside. If so it is shot. I would replace it
because my time to repair it and my past success rate with patching would
cost me more than the price of a new one. Just my opinion, others may have
more time and a better method than myself. Just for the record, I patched
one with 2 part liquid epoxy once and it only lasted until I got home.
There is probably something already recorded in our List Library please
check it out. - E.W. Blake

I reconditioned my petrol tank last winter but there is still some crud in
the fuel lines. Every once in a while a smal piece of rust gets through the
screen and stops the needle valve from closing completely. This produces
the same symptom as a non-floating float. Cleaning out the screen and the
needle valve fixes it. - Bruce Cunningham

Jim, While messing with the float, I went ahead and replaced the float
valves with grose jets. - E.W. Blake

Bruce, And here I thought that in Vermont these kind of problems were
caused by ice. Anyway, might this not call for an in-line fuel filter. -
Klaus Nielsen

Re the sticking fuel valves or floats - I had this flooding problem on and
off for years on my 150 S and never worked out what it was.  I changed
needles and seats regularly and tried everything I could.  Eventually I
swapped the fuel bowl on the troublesome carb for a new one - solved the
problem, but never found out the real reason. Regards, John Elmgreen

Often the problem is a small piece of 'crud' that gets up as far as the
float needle. Before you start tearing the float chamber apart give the top
of the chamber a good wack with the handle of a screwdriver. This will
sometimes disslodge the 'crud' and the needle will seat properly. To stop
any problem of this sort I have installed 2 inline fuel filters. One
between the tank and fuel pump and the other near the carbs. No problems
for about 4 years. Just change the filters regularly. There seems to be
more of a solvent action in newer types of gas. I have noticed in some
service stations there are now inline filters on gas pumps. Are the gas
companies aware that their gas is dissolving crud in underground tanks? -
Bill 1955 XK140OTS

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