Howdy folks,

I am in the middle of a quest so that I can banish a P0440 CEL with the goal of passing emissions in the freestate of Maryland.

So far, I replaced the fuel cap with a Genuine new GM cap and I also replaced a rusty filler neck that looked very questionable. While I have not resent the CEL, the light has not gone off of its own volition as I think that it would otherwise do if there was still not a problem. I crawled back underneath to inspect all of the wire connections, fuel lines and hoses underneath around the evap canister, the vent solenoid, and the fuel filter. Everything looks sound, I disconnected each and every connector and inspected every individual wire. They all check out.

It was then that I noticed a stray plastic tube coming from off of the top of the fuel tank parallel to the fuel lines and the electrical lines. I tried watching a few Youtube vids and one was on a 98, another was on a 2002, and another was on a 2004. Between the shaky camera and lack of thorough explanations I could not locate this last tube. There is nothing that it even reaches. It is on the left coming out of the routing clip as you look at it right side up from the back of the car. Could it be a "breather" as I heard mentioned but no pointed out in one video? Is it missing a part.

Maybe it is the curse of the half-breed split year Frankencavaliers that 1999 models truly are.

Here is a picture that I added as an attachment.

I hope you all can see it and supply some opinions. Is it even a factor in my P0440?

Thanks!

Attachments

SmallHose.jpg (286k)

Havme you pulled the tank down to physically look at the pump and lines? There should be 3 lines coming from the top of the fuel pump module. Fuel pressure, fuel return, and the vapor line. The vapor line should be going to the canister and evap system.




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To review, I have (5) items passing from the routing clip from the fuel tank top as seen in the picture. The left one is the mystery, next is the Evap line (ridges), followed by the 2 fuel lines and then the harness to the vent valve solenoid.

I have not dropped the tank (yet) but I went back to confirm the items from the routing clip.

An examination of the Evap canister itself has all of its connectors accounted for. The largest one to the fuel tank, the wiring connector and then the smaller tubing one that connects to a steel line that presumably makes its way up front to the intake. I notice that before the smaller evap tubing line connects to the steel line that it is plastic tubing that resembles the kind that the stray and unaccounted for line from the fuel tank line and wiring routing clip seen in the picture is made of.

I am baffled as to what the purpose of this extra line could be. With it wide open could it be the cause of my P0440 CEL? Is it a breather? I thought the fuel systems were closed so there would be no venting to save us all from the horrible VOCs and HAPs.

If I drop the tank and it goes to another connector from the pump and sender I still won't know a thing.

Any suggestions?

As far as our CAVs go, the 99 is a real bastard year...

thanks.

it doesnt go to the fuel pump, it goes to a different component ontop of the tank, that is part of the evap system. click here to see my old thread. On the top of the fuel tank, you will see a canister looking thing inside the tank next to the fuel pump. the big hose coming off of it goes to the square canister, and the small one is that vent tube your referring to.



"If I'm not back in 5 minutes...just wait longer"

Thanks for the reply, I lowered the tank to get a peek and it was just like you stated. There was the evap line from the pump too but that joins the main evap line from the bulkhead through a "Y" type connector. As I mentioned earlier, every other diagram or view I saw of a cavalier tank did not have that second tube coming off the evap bullhead. When I looked you had not posted yet and I was thinking that someone shagged that evap bulkhead with the extra fitting from some other sort of car. (Given the satiate I go this car in it would not surprise me a bit!) I still have the P0440 and having a wide open tube coming from the same fuel tank bulkhead is likely not good so I corked it. My CEL did not go off but the cars running has not been affected either. I was able to fill up with gas with no problems or differences either.

Based upon what you are saying though, this tube is a 99 only sort of thing and connects to nothing.

Time will tell if my cork does anything bad...