Resolved : GM 3100 P0441 code in 1998 Buick Century

[mongo]

Just thought I would post this here since I could find no accurate answer anywhere on the net. The backround:

My Son's 1998 Buick Century with a fresh 3100 in it periodically set code P0441 and NO OTHER CODES. Six months ago it came on permanently. New gas cap, no dice. New purge valve, no dice. Checked Vent Valve, no dice. Several sources on the net indicate this CANNOT be caused by a vacuum leak (WRONG).

I got desperate and built a "smoker" out of a paint can and some dollar store incense. Smoked from the front and since the cannister vent is normally open, it leaked from there back by the gas tank (normal). So I smoked the tank from the filler neck and smoke started pouring out under the car.

There is a metal vent line that follows the filler tube and filler vent under the car near the tank. There is a 6 inch piece of 3/4 inch flexible tube between this line and a plastic t-fitting in another line. This 6 inch piece had a hole in the top that you could fit your finger tip in. Looked like maybe a rodent chew or just old age caused it to disentergrate. Replaced this piece of tube with some scrap line from the garage and the code cleared in just a few minutes.

[LeftVentricle]

Thank you for posting this! Those EVAP codes can be a bitch to track down and fix.

[mongo]

No problem. I hope it helps someone else out since I expect this same hose is present on Malibus, Centurys, and Grand AMs. The smoke can cost between $20 and $30 to build. For posterity's sake, here is what it was and how I used it:

1 New metal 1 gallon paint can from Lowes ($7)
2 ea 1/4 inch NPT air fittings ($4)
1 ea 10 ft roll of clear vinyl tubing ($8 )
1 ea 2 inch "rubber" PVC pipe cap ($3)
1 ea box of dollar store incense ($1)
1 ea chunk of hard dollar store floral foam ($1)
1 ea lighter ($1)
1 ea Slime Brand schrader valve tool ($2)

I drilled two holes in the lid of the paint can and used plumbing solder to affix/seal the fittings. I used a small pancake compressor on one fitting regulated to under 5 lbs of output. I drilled a 1/2 inch hole in the 2 inch pipe cap and pulled 6 inches of clear tube through. I pulled the (reverse threadded!) schrader valve from the EVAP test port above the brake booster under the hood. I put 20 short sticks of incense (I cut 10 in half) into the foam block and lit them, and dropped it into the can. I stuck the clear tube on the other fitting and made sure I had smoke.

I started at the test port up front. The smoke should flow freely into the system as the CANNISTER PURGE VALVE back by the gas tank is normally open. Once you see smoke coming out there, you know the system is full and you can look at the lines up front and trace them along the frame rail on the drives side looking for leaks. If that come up good, remove the gas cap and stick the 6 inch leader into the tank. The 2 inch pipe cap should seal fairly tightly around the outside of the filler neck. Wait a second and check for leaks in the filler and vent lines. That is where I found mine.

Common leak points are on vehicles with multi-part filler necks as they have crimped in seals that fail between the pipe sections. That is what I EXPECTED to find but mine had a one piece neck. Any car with rear end damage may have a cracked vapor canister (behinde the drivers rear wheel).