1996 Geo Tracker Check Engine Light

[fixkick]

great, but it can take 3 driving cycles for some DTC to  set.  (OBD2 is very tricky rules and only reading the first PDF above, shows  this.
if you blow into the can hose, it is free air vented.  the can has 3 holes, 1: vent, vacuum to VSV and one hose to the take via regulator.
also the VSV valves are defaulted to open (with key off, so only key on 12vdc there are closed yes tricky but all VSV on this car work backwards key off.
id wait to see if it fails with tight cap or new cap on tank.  there are like 50 test to check the whole system ,  leaks, many, valves 3,  vacuum hoses bad, pressure sensor bad, tank rusted through the top center tank has plastic silly vapor baffle 6ghttp://ge.tt/6gvplbp2/v/17vplbp2box  that can crack.  the list is huge, for leaks, in shop or any smog station test 1 in with special cap with a hose fitting on it.
then they do a leak down test in 5min work if that passes then there are no tank leaks or vents leaking in the rear, all  in 5 mins work , leaving all the easy stuff up front to  test, 1 by 1.

SEE HERE I TOOK THE PDF ABOVE AND CUT THE PHOTO OUT OF IT AND ADDED RED HOSE LETTERS
which hose did you blow? on.
the tank pressure test proves all is ok from E to the right side,  all in 1 test. the 1/2 PSI pressure leak down test it is called if fails we hold that pressure with shop air and1/2 psi paint regulator (shops use nitrogin gas) and use spray bottle and find where the vents leak, bubble test. just like finding heater natural gas leaks. same deal.

when car starts and moves down there road, valve 7 opens. letting vacuum  can-tank #4
and valve 11 opens to let in fresh air, so that fresh air, lets the canister, flood with clear  fresh air and engine sucks all gasoline fumes and burns them.
engine off, ,both those 2 valves above are closed, preventing fumes, from leaving the CANISTER as you sleep, etc.

all other parts there electric are self tests DTC tests.  like 443 . valve 9 is a 3 way valve,  i think it can artificially open regulator #2 and it  opens. E to B/
valve 9 i think, at its bottom arrow, means vent port.
if a filter is seen there,that vent port. and normally D pipe goes to vent making the regulator work at 1/2psi.