OK, It's taken over a month, but we finally sorted this out (see below
for original symptoms)
I went through and replaced pretty much everythng with spares; needle
valve, float, pin. No change. Checked the fuel pressure, and found it
right at 3 PSI just like a good little SU fuel pump should be giving us.
Finally got smarter, and removed the float bowl like, hooked up the fuel
line, and held the float closed. Drip drip drip. . . aha! Fuel is
coming from under the float valve. The shim/sealing washer isn't. Daddy
does a little happy dance and replaces the sealing washer with an
aluminium washer from our local hardware store on steroids.
It's still leaking fuel.
The car is still running like cr@p so I decide to look at the plugs and
check the mixture with the colortune on the theory that the shaking is
causing excess fuel in the float bowl. #1 plug is fine. Colortune
reveals reasonable mixture. Not spot-on, but good enough to run better
than it is.
#4 plug is this virginal, new-plug white. The nose test confirms no gas
in #4. Hmmm. . . no gas in carb throat either. I definitely have gas in
the float bowl. Pull carb, remove jet.
My dear son, who otherwise did an excellent job reassembling the carb,
let the jet tube slip out of its rubber sealing washer, then tightened
down the retaining nut. It mashes the sealing washer into the bottom of
the float bowl and seals it tight. No gas coming out of there -- ever.
Replace the jet, and life is pretty good again. No fuel leakage. Now I'm
getting the needles and springs sorted out. I'll get back out there this
morning and redial the carbs.
This was an ultra-wierd problem. Hey maybe it'll make a story for the
Model Garage! :-)
Thanks to all who offered suggestions. It's nice to know we're not alone
with our cars.
Cheers,
Dave Ambrose
Paul Asgeirsson wrote:
>Stuck float, dirty seat, bad needle?? Not closing allowing fuel out
>the overflow..
>
>I'm not the right guy either!
>
>
>
>>Greetings O Learned Ones:
>>
>>My son and I just mounted some newly rebuilt carbs on his desmogged '70
>>midget. We turned on the key, and have gas coming out the "spare" hose
>>connection on the rear carb. I don't remember us having anything on that
>>connection previously so I'm both puzzled and concerned by this sudden
>>production of liquid petrol. Did we get the carb lids swapped? The
>>emission control diagram seems to indicate that is normally a vent of
>>some sort that runs to the carbon cannister.
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