P0455,evap system leak (large)

[98TrackerMan]

Howdy All. 1998 Chevy Tracker 4cyl-4wd-4Dr-98K mi.on it.
Got a "service eng. soon" light- got out the OBDII and came up with code P0455,evap system leak (large). - where should I start & what should I do about this one? So far i cked the gas cap. It is tight and is a new one. I replaced in oct 2015 to clear that previous 2015 code. I do smell a slight odor of gas after I parked in my yard. At first i thought it was because i just filled up....but than the Eng light came on in the AM on next start up. weather supposed to be nice this week -I guess I'll be crawling around!-Ha
Thx- 98TrackerMan

[fixkick]

if the caps seals,and you reset 455s
and it comes back you have an EVAP breach.
it is a large leak
there are only 2 ways, besides, looking for rusted top of tank or hose cracks
that is pressure testing or vacuum testing it, called a leak down test.
one way is use a LPHV spray paint gun regulator, set to 1 or 2 psi, lowest possible (got shop air?)
then pressure the system.
then listen for leaks using a rubber hose to ear.
and or use soapy water to find bobbles, same way the gas man finds gas leaks on furnace leaks.

http://www.fixkick.com/sensors/EVAP/Evap-testing.html

that smelt fumes is wrong.

[98TrackerMan]

Thx for the quick reply - guess I'll have a little work to do this week inspecting the problem-maybe the fumes is coming from a cracked hose?
- I'll be cking out the link you sent. Have to ask around for a LPHV spray paint gun regulator,
But yes, I have air-& soapy water!
Thanks again fixkick , - Regards 98TrackerMan

if the caps seals,and you reset 455s
and it comes back you have an EVAP breach.
it is a large leak
there are only 2 ways, besides, looking for rusted top of tank or hose cracks
that is pressure testing or vacuum testing it, called a leak down test.
one way is use a LPHV spray paint gun regulator, set to 1 or 2 psi, lowest possible (got shop air?)
then pressure the system.
then listen for leaks using a rubber hose to ear.
and or use soapy water to find bobbles, same way the gas man finds gas leaks on furnace leaks.

http://www.fixkick.com/sensors/EVAP/Evap-testing.html

that smelt fumes is wrong.

[fixkick]

good, have air. must be carefull not to use too much pressure. even 1/2 PSIis plenty.
there can be other failures , all valves there are suspect. if stick open.
normally the fumes collect in the EVAP tank and can not stink.
my guess is there is a simple breach. (nose told you that)

there are 3 methods,
air, or inert nitrogen.(plus soap spray)
vacuum tests, find it. (soap bubbles not work here, only listening for hiss leaks)
or smoke machine. (see smoke , bingo)
and the horrid way take all parts off car, test each 1 by one, for leaks. (yes, a real pain)

if lucky air pressure applied and a rubber hose held to ear and moved about, all places vent hoses, you may hear that hiss..
can be easy way,,, of all.