2000 V70 Fuel tank will not hold pressure.

Derekw66 · Post by **Derekw66** » 28 Apr 2015, 18:32

Hi guys, I know emission issues have been beaten to death but I can't find an answer to my particular problem. I have that pesky 0442 code and have checked out all of the hoses. All are good. While verifying the integrity of the fuel pump gasket I decided to pressurize the tank and listen for leaks. I found the bottom of a canister up high on the fuel filler neck was allowing the air to escape. The top of the canister goes to the charcoal canister but the bottom is open. I tried it with the igition on and off thinking a valve controlled it but had the same result. I havn't seen a schematic that had anything connected to the bottom of the canister but it does look like a 1/2" hose would go on it because it is ribbed on the end. If I put my thumb over the hole I can hear the fuel cap start to leak. Anyone have any insight as to why this would allow all the air to immediately escape? I am thinking this is whats causing my light to stay on.

Post by **Ozark Lee** » 28 Apr 2015, 18:57

I'm having a bit of trouble trying to visualize the components you are talking about - not your fault since that area is much more complex than it really needs to be. It almost sounds like the hose to the rollover valve is gone. Is there anyway you can snap a picture of the area in question and post it back?

...Lee

Post by **scot850** » 28 Apr 2015, 20:38

This is your lucky day! This area sounded familiar and as I have just dropped the rear sub-frame and fuel tank/filler on my 2000 R, it was easy for me to go take a quick few photos for you both to discuss.

: Fuel filler neck lowered

: Lower down about 10" from top with plastic canister

: Pipe from canister on filler neck

: Where pipe goes to is can in middle

The can is I believe the shut-off valve. Pipe from filler neck can is the one entering from the lower right of the picture.

Hope this helps,

Neil.

Derekw66 · Post by **Derekw66** » 29 Apr 2015, 05:37

Thank you Neil, the pics are perfect. The 2nd and 3rd pic are great shots of the canister I am talking about. The nipple on the bottom is where the air blows out of when I pressurize the tank. Car runs great and fuel mileage is 28-30 mpg. No issues refueling either.

Post by **scot850** » 29 Apr 2015, 16:48

I'm not sure on the operation of this part, but I believe it may be vented to atmosphere so that as you fill the car, it does not over-flow. There is no pipe attached to the bottom of it and it is called an air filter. So I suspect the part is operating as it should, but perhaps someone else can advise if there is a one way valve in there so when the evap system checks for leaks, it is not holding a vacuum. But then this could be true of any part of the system.

Sorry, can't help more as I'm not experienced enough on how all the parts of the system work.

Neil.

Derekw66 · Post by **Derekw66** » 29 Apr 2015, 17:57

I also tested the evap control valve and with an external 12v, it opened and closed perfectly, but with engine running and the cars connector attached, the valve doesnt close. Checking the pins for voltage showed 8.5v. I havn't traced the wires back yet, I thought the valve needed 12v and got it when the engine is running. Can anyone shed some light on that? Thanks.

Post by **Ozark Lee** » 29 Apr 2015, 21:05

Is this a turbo or a N/A car? Do you have any idea which ECU you have?

Typically the ECU controls the purge valve but I don't know if it supplies the voltage or goes to ground to complete the circuit to activate it. Most of the time it is the latter but knowing which ECU you have will get me to the correct schematic.

...Lee

Derekw66 · Post by **Derekw66** » 30 Apr 2015, 10:27

It is a non-turbo. Hopefully the picture shows which ecu I have.

Post by **98v70dad** » 20 Jan 2016, 11:00

I am having the same issue with the 8.5V instead of 12V at the purge valve. Did you ever figure out the cause and how to fix it?