>but I wonder how long until a new one
> gets saturated?
That piece should last the life of the truck. It is full of little
charcoal granules. The charcoal 'holds' the fumes. The mass of
granules is held under pressure by a spring-loaded flap under the top of
the cannister.
It doesn't made sense that the piece is there and a line is going to the
fuel tank, but the purge system is missing. It had to have been
removed. Just the purge system being 'optional' doesn't make sense
either. I'd either head to a Ford dealer for some help, or find a
similar truck and check out it's system. Car lots, junk yards, Ford
truck clubs would be good sources for info. Try asking your question
here:
www.ford-trucks.com
That group should be able to help.
Dave S(Texas)