[ihc] Milage question

[David Bongo <dbongo@xxxxxxxxx>]

I've been tracking the milage on my Scout, and I've noticing an odd
phenonom.  When the truck is run every day I get good milage (definied
at 7.5-8.0 mpg on 87 octane gas).  But if it sits for 1 or 2 days
between fill-ups, it drops way down.

There is a slight gas smell (or, if you wish to be grammatically
correct, "gasoline odor") around the rig.  So, my questions would be:

1> Could enough gas evaporate to make a difference?

2> What could be the cause of the smell?

I've got a 33 gallon tank, with most of the vent lines welded shut. 
One leads to a charcoal cannister which isn't even hooked up correctly
(the nipple for the vaccuum line is broken off, so it gets just the
tank and carb vents) and the other dead-ends and is blocked.  I've
also got a new, locking, non-vented gas cap.

The only possible thing I can think of is the complex menagerie of
pipes (some sort of vapor recovery thing) that is connected to the
filler neck and tank...except it's not connected to the tank.  I
haven't popped the panel off the interior of the rig yet to inspect
the setup, so it is just a theory.  Any other ideas?

Oh, as for the difference:  I gassed up on 8/7 and 8/10.  In that time
(which included one Sunday where the rig didn't move) I got about 8.5
MPG.  My next fill-up was on 8/21 (yes, a whopping 11 days) and I got
under 7.4MPG.  Game gas, same station, heck, I even used the same
pump.

Dave