Message text written by INTERNET:Harrymague@aol.com
>Thanks for the reply Randall. With the engine running, shouldn't there be
a
vaccum apply to the canister throught the ARS. I thought the ARS activates
to shut off the vaccum supplied by the intake manifold depression. So if
that is the case, the line that runs to vent the carb float chamber should
have a depression and the vent line switch controls whether it is vent to
the
canister or back to the carb???
<
Harry,
The vacuum from the manifold goes directly to the valve and when the valve
is deactivated the vacuum stops there. The bottom port of the canister is
connected to atmosphere.
The slight depression from the venturis (the large hoses connected to the
right side of the carbs) connects to the top of the canister as do the
lines from the carb float chambers and the tank vent line. However, there
is an orifice in the port for the vneturi lines (that causes a whistle in
my car) that will reduce the depression applied to the carb float chambers
to zero since the canister is vented to atmosphere through the charcoal and
the anti-run-on valve. (The venturis also purge the crankcase by drawing
the blowby gases from the valve cover. The blowby gases will be replaced
by air leaking in through where ever it will leak in. But that's another
story.)
When the engine is shut off 12 volts is applied to one side of the ARS
valve coil, the other side of the coil is grounded through the oil pressure
switch. The valve actuates and applies manifold vacuum (from the intake
manifold) to the charcoal canister and the carb float chamber. The vacuum
will draw the fuel away from the jets and starve the engine of fuel.
Your symptoms sound like vacuum is applied at a time when it shouldn't be.
Either the vacuum is coming from the manifold or from the venturis.
My first guess is a malfunction of the anti-run-on valve. Trace the vacuum
line from the valve to the intake manifold and disconnect it from the
manifold and cap the manifold tap and try again. It this solves the
problem then check to see if the valve is stuck open (you can stick your
finger into the bottom port and press the valve plug up against the spring
if it is operating properly). If it is stuck it is likely stuck in the up
position which will apply vacuum to the canister and hence the float
chambers all the time.
If the valve works freely then disconnect one of the wires to the valve and
test again. If this fixes the problem then you have a wiring error. This
could be a problem with the keyswitch.
Another possibility is that the canister is plugged and venturi depression
is applied to the carb float chambers. The carburettor works on the
principle of a difference in air pressure between the venturi and the float
chamber but this condition makes the air pressure on both sides of the jet
the same and fuel will not flow.
So, check out the valve and pull the big hose from the canister and see
which source is the cause of the problem.
Good luck
Dave
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