2000 SL2 MIL - EVAP system small leak

I can't remember the code number to this off the top of my head, but I keep getting the Check Engine light on due to an intermittant EVAP system small leak detected. I already replaced the gas cap, cleared the codes, and the code still resets after a week or so. I even verified the old cap was not at fault by installing it on a 1999 SL2 with no codes set on that vehicle after 2 months. All the Saturn techs I talk to are scratching their heads on this one, because the new gas cap usually fixes this problem. Anyone got a clue what could be at fault?

i'm going to cover a few ways of looking at it.

first, a few little tips from a old saturn tech(wolfman for those who know)

1. Bad gas cap.
2. Loose rubber sleaves on filler pipe to tank junctions causing a vacuum leak
3. Bad/loose wiring to the sensor at the splice pack located under the carpet, driver's side trunk wheel well area.
4. Loose or bad hose connection at the carbon canister, CCPS (carbon canister purge solenoid) or tank vapor line at the tank.
5. HOLE in the gas tank. (Seen people drill right into the top of the gas tank on occasion when installing a stereo amp in the trunk area of the car)

2. i have heard of a one or two EVAP codes cause by a blown EGR fuse.(DTC P0443 IIRC)

3. my advice - jack the car up as high as you can and inspect EVERY FUEL COMPOINT. after that my next step is a little dangerous. if you have access to a air compressor(like for impact tools), pressurize the fuel tank and EVAP lines, just 3-5 psi should be more then enough. with any luck you should be able to hear a hissing noise. i have heard of special floresnt dye that shows leaks with a black light, but i have never used one myself. you might beable to search the internet for the stuff, or someone in the "Automotive Forums .com > Cars in General > Engineering/Technical" forum here http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=670

if no leak is found, there is a very small chance the sensor is bad

if no luck prevails, try saturnfans.com

Thanks for shedding some light. I'm an old Saturn Tech myself, but never had a case where the gas cap replacement didn't solve the problem. I got a few questions though:

1. If it's possible that a blown EGR fuse could trigger an EVAP code, could a intermittantly sticking pintle in the EGR valve cause an EVAP code as well?

2. You said the sensor may be bad. Which sensor are you referring to?

Thanks again

1. i highly doubt it.

2. i honstly don't know much about the sensor(my wiring diagram is OBD-1) i assume its in the gas tank. my understanding is the fuel tank is always under a small amount of vacuum(hence the hiss when you remove the cap). some where there is a pressure sensor, if that sensor doesn't detect a vacuum, then the computer knows there is a air leak somewhere.

someone on saturnfans.com may be able to go into more detail about this for you.