fixed mine by replacing the check valve on top of the gas tank.
drop the tank pull the old one out put the new one in. been good for 5k miles now.
I had the 446/440
I recently purchased (5) 4Runners. All 1997 except the 2001 that is throwing the 3 codes.
The PO of the 01 spent a couple of thousand on shocks, tie rod ends...... Vehicle is clean inside and out. Had a little rust. My son and I welded one 2" piece of steel over a section of the frame on the drivers side that had 4 small rust areas. We had this up on 12 ton jack stands and cleaned the undercarriage. We dropped the gas tank so we could inspect the driver side frame and floors. We used a phosphoric acid solution diluted with H2O to convert any surface rust we found and then painted the entire underside with a paint over rust product. SEM Rust Shield I think was the product. We used the hardner also. Now we feel very comfortable with the integrity of the undercarriage.
When we dropped the tank we noticed a broken off vent pipe on the top of the tank. Upon further examination, there was a small hole in the top of the tank where a bracket was once mounted. We ordered a new tank and installed it using the old Check Valve.
Another thing we noted was the accordion style hose that goes from the Check Valve to the EVAP canister was damaged. I don't even know what they call it and have not been able to find a part number or replacement for it.
We did however find a very good piece of rubber hose that was able with effort to be worked onto the damaged hose. We cut the damaged place out of the hose and caked RTV onto the accordion hose and put the Rubber hose on top. I truly think that hose is sealed and not leaking.
We would have thought that the holes in the gas tank and holes in the accordion hose would have solved the multiple CEL's.
We did check all the valves two under the hood and the one on the canister with 9volts to hear a click. All the valves clicked.
After everything we did we felt that assembly of the vehicle was in order and we would drive it to see if the codes would stay gone. They all came back.
We did not perform a proper test on the canister because we only purchased one vacuum pump kit and the video we had showed we needed two. After everything we have been through to that point, it seemed likely that the problem was fixed and if it was not the removal of the EVAP canister would be an easy job.
This week after the check engine light came on, we checked the codes. 440, 441 & 446. I read someplace on this forum how someone had replaced the filler neck and successfully eradicated the CEL. I read it several times but was not clear if they had the 446 or not. It seems that some people say that 446 is either canister or VSP on canister.
My logic would make me think that if a gas cap seal or a vacuum line seal is so important, then a hole in the tank would have the same detrimental effect. Furthermore a compromised filler neck tube would also not allow the system to seal.
I did reach up and touch the filler neck tube and noted flaking softish metal on the topside of the metal tube. It seems like if it is not leaking, it is a problem waiting to happen.
Some people dread the canister replacement. Finding a replacement filler neck for a 2001 4runner that is in stock is no easy task. I found some that were not available for as little as $108 but no stock. I found one for almost $150. Not a cheap price and I would have to think that replacement will not be a fast simple task.
We have a clock ticking. Here in CT a new registration of a vehicle that came from out of state has 60 days from the time of first emission test that fails to take another free test. If you don't pass in 60 days they suspend your registration. The first time the vehicle failed because it was not OBD ready so no codes were identified. I knew there were codes when I purchased the vehicle out of state but had cleared them prior to emissions. With a failed emissions you can to to DMV and register the vehicle with the aforementioned 60 day rule. Another thing I think is that in CT if you fail emissions you can get a waiver after you spend a certain amount of money on emission related repairs so long as your repairs has shown improvement in the emissions system. When purchased there was also a 420 code Catalytic converter code. That one has not yet reappeared. I don't mind fixing the vehicle, I just need to keep it on the road. I am hoping for all codes to be back this week and to go back in for my free inspection and fail. Then I have documentation of the codes and not just a not ready OBD failure. Then we can prove we replaced gas tank, filler neck, and whatever else. Worst case scenario I am hoping for is to have failed emission and receive a one time waiver because we spent the limit on parts trying to fix the problem.
The worst part about these issues are the necessary drive cycles and time they take. If I have a plumbing leak or a swimming pool leak, I can fix it and know right away it is fixed. With these emission issues and time it takes to complete drive cycles there is a lot of time and money thrown at the fix.
I have read plenty on this forum in regards to this issue. Many will suggest bringing it to a dealer. I have read many people say they did bring to a dealer, was diagnosed as faulty xyz and 200 miles later light back on.
Open to any and all help or suggestions!
