Incontinent Carburetor

Why has my carb (Solex 28Pict1) suddenly taken to piddling gas when
(but only when) the engine is shut down; and can I fix it?

It drips for about 10 seconds or so like there's some pressure forcing
gas out, it is visible at the throttle shaft but hard to say where its
originating from. Happens both with a hot engine and if its only been
running for a few minutes.

If it were worn throttle shaft bushings, wouldn't it leak all the
time? And wouldn't a leak manifest itself as an uneven idle from air
being drawn in? My idle is steady and the leak only appears on
shutdown.

I have tried replacing the fuel shut-off needle valve which hasn't
helped the situation. I've tested the float for leaks and it appears
sound. Could I try lowering the float level by adding another gasket
underneath the needle valve?

I've also been told that this is normal and that there's nothing I can
do about it but I'm having trouble buying that, gas dripping onto a
stinking hot manifold cannot be safe.

Some advice would be welcome...

Dangermouse wrote:

> Why has my carb (Solex 28Pict1) suddenly taken to piddling gas when
> (but only when) the engine is shut down; and can I fix it?
>
> It drips for about 10 seconds or so like there's some pressure forcing
> gas out, it is visible at the throttle shaft but hard to say where its
> originating from. Happens both with a hot engine and if its only been
> running for a few minutes.
>
> If it were worn throttle shaft bushings, wouldn't it leak all the
> time? And wouldn't a leak manifest itself as an uneven idle from air
> being drawn in? My idle is steady and the leak only appears on
> shutdown.
>
> I have tried replacing the fuel shut-off needle valve which hasn't
> helped the situation. I've tested the float for leaks and it appears
> sound. Could I try lowering the float level by adding another gasket
> underneath the needle valve?
>
> I've also been told that this is normal and that there's nothing I can
> do about it but I'm having trouble buying that, gas dripping onto a
> stinking hot manifold cannot be safe.
>
> Some advice would be welcome...
>

Might be fuel pressure building after shutdown,
but I'm surprised it does it on a stone cold engine.

Add a fuel pressure regulator?

Speedy Jim
http://www.nls.net/mp/volks/

"I have no use for a car which has more spark plugs than a cow has teats!"
Henry Ford, when advised that Chevrolet was introducing a 6-cylinder engine.

> I've also been told that this is normal and that there's nothing I can
> do about it but I'm having trouble buying that, gas dripping onto a
> stinking hot manifold cannot be safe.

Just a thought ...

Could be the fuel pump. I have found that Mexican and Brazilian fuel
pumps tend to push too much fuel pressure. You might try adding
another gasket under the fuel pump to see if that helps with the
problem.

Well I thought about it and thought about it and I decided it HAD to
be related to fuel shut off at the needle valve so I went back in
there for a closer look and spotted what I had up until now been
missing.

My carb is supposed to have the thicker, 1mm gasket under the valve
(which is what I had put on) but what I hadn't noticed was that some
PO had previously shoved a thin, metal gasket up into the gasket
recess, leaving it flush with the surface of the carb top. I dug it
out of there and refitted the valve plus appropriate gasket. I haven't
had a chance to determine yet if this has fixed the problem but I'm
thinking its highly likely that it'll help some...

Hopefully a simple fix and a lesson learned.