The vent line you rigged should do OK. There isn't a lot of air that
passes through the line (it's merely replacing with air the volume of
fuel that is moved) so I don't think that the vent is the problem.
Check the float valves again. They can get stuck from the tiniest
particle of grit, and there is likely to be some dirt dislodged any time
a carb is opened. There may be one sticking open. A test for that would
be to disconnect the vent line and to see if fuel flows out from it when
engine is running.
Another vent line that can fill up the charcoal cannister is the line
that runs back to the fuel tank itself. Again, air has to get into the
tank to replace the fuel being withdrawn, and this air goes back from the
cannister to fuel separator to tank. If that line gets plugged and that
tank filler cap is not vented (it should be a non-vented cap on a car
with this vent line) and the gas in the tank expands on a warm day, then
fuel expands and pushes into the cannister via the overflowing carbs.
The quick&dirty check on this is to loosen the fuel filler cap when you
notice the cannister flooding. If fuel blows out of the cap onto your
pants, this vent line is clogged.
Do you know the pressure developed by the aftermarket fuel pump? SU
pumps deliver only 3-4 lbs or so, lower than most. If this pump is
delivering more, it may be overpowering the otherwise-adequate needle
valves.
Bob
On Tue, 30 Sep 2003 05:24:10 -0400 "S Twigg" <seanan@crosslink.net>
writes:
> Everyone,
> I in the midst of converting my 75B from the ZS to a set of
> HS4's from a 1970 (AUD405F & R). My problem lies in the fuel vent
> line.
> I created a T to connect the two lines from the front and back fuel
> bowls to the single vent line that went from the ZS to the carbon
> canister. After I had everything connected correctly the vent line
> proceeded to fill the canister with gas and I believe the engine was
> flooded - that is when I gave up for the day.. So obviously
> something is wrong with the equation. I know I need to check float
levels but
> is there anything else? Also, anyone have thoughts, ideas, and/or
> pictures on how all the hoses should run?
>
> Other info relevant or not; jets centered, I thought floats were ok,
> emissions all still attached, brake servo attached to intake, an
> aftermarket fuel pump (long tube shaped one) that seemed to give ok
> fuel pressure with the ZS.
>
> As usual, any and all help is appreciated.
>
> Thanks,
> Sean Twigg
> 75B
> 71XKE (I'm just the mechanic for that one)
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