Vacuum in gas tank - already replaced almost everything

[DonnieBrasco]

2003 Yukon has been throwing the code for the fuel evap (445 and/or 446?) for a while now. As far as I know, this code and the vacuum associated with it can come from one (or more) of four areas:

(1) Evap/purge unit on engine block;
(2) Evap/purge unit under the car near the tank;
(3) Charcoal canister under the car near the tank; or
(4) Gas cap

I've already replaced 1-3. I didn't replace them all at once, but rather one at a time to see which one (if any) would remedy the problem. The last thing I replaced was the charcoal canister which I did this weekend. And I'm still throwing a code and getting a vacuum in the tank.

The only thing I haven't changed is the gas cap. I saved it for last because I was sure it had to be one or more of the first three. But, if it is just the gas cap, could that be throwing a code? I didn't think it would because it's not electrical.

This is frustrating. What are my next steps? I'm thinking it's most to do with an electrical component not operating one (or more) of the purge units. Thoughts??

 

[HiHoeSilver]

2003 Yukon has been throwing the code for the fuel evap (445 and/or 446?) for a while now. As far as I know, this code and the vacuum associated with it can come from one (or more) of four areas:

(1) Evap/purge unit on engine block;
(2) Evap/purge unit under the car near the tank;
(3) Charcoal canister under the car near the tank; or
(4) Gas cap

I've already replaced 1-3. I didn't replace them all at once, but rather one at a time to see which one (if any) would remedy the problem. The last thing I replaced was the charcoal canister which I did this weekend. And I'm still throwing a code and getting a vacuum in the tank.

The only thing I haven't changed is the gas cap. I saved it for last because I was sure it had to be one or more of the first three. But, if it is just the gas cap, could that be throwing a code? I didn't think it would because it's not electrical.

This is frustrating. What are my next steps? I'm thinking it's most to do with an electrical component not operating one (or more) of the purge units. Thoughts??

It can certainly be the gas cap, but only get an OEM replacement. Problems with aftermarket. The other common cause is charcoal pellets from the old canister clogging the lines. Did the old one rattle when you removed it? You can pull the lines to it at blow them out.

 

[bigfootchiro]

Could also be a leak in the filler neck from cap to tank.

 

[DonnieBrasco]

It can certainly be the gas cap, but only get an OEM replacement. Problems with aftermarket. The other common cause is charcoal pellets from the old canister clogging the lines. Did the old one rattle when you removed it? You can pull the lines to it at blow them out.

Thanks dude. So if it is just the gas cap, that could throw a code? I guess the creation of the vacuum would be throwing the code? The old one did not rattle. And I tapped it on the ground and didn't see much if anything fall out. And I was able to blow through the ports, which was my first thought that this might not be the culprit.

Could also be a leak in the filler neck from cap to tank.

Thanks. If it was a leak though, I wouldn't think that would pull a vacuum but rather the opposite. Or am I thinking about it wrong?

 

[Rocket Man]

Thanks dude. So if it is just the gas cap, that could throw a code? I guess the creation of the vacuum would be throwing the code? The old one did not rattle. And I tapped it on the ground and didn't see much if anything fall out. And I was able to blow through the ports, which was my first thought that this might not be the culprit.


Thanks. If it was a leak though, I wouldn't think that would pull a vacuum but rather the opposite. Or am I thinking about it wrong?

Those codes are for evap system leaks, not too much vacuum.

 

[HiHoeSilver]

^^^this. Evap leak.

 

[DonnieBrasco]

Those codes are for evap system leaks, not too much vacuum.

^^^this. Evap leak.

Sooooo...basically I'm screwed? Obviously it's not a leak in any of the three things I've replaced. How would I even go about tracking that down? I probably have a year or less left in this vehicle, so I may just ride it out.

 

[HiHoeSilver]

Sooooo...basically I'm screwed? Obviously it's not a leak in any of the three things I've replaced. How would I even go about tracking that down? I probably have a year or less left in this vehicle, so I may just ride it out.

Gas cap.

 

[DonnieBrasco]

Gas cap.

Thanks brother. Just ordered an OEM replacement.

 

[HiHoeSilver]

Thanks brother. Just ordered an OEM replacement.

Let us know if it works.