Vapor Tank Question

[Zed Head]

19 hours ago, chaseincats said:

This hit me today.  Why not plug the metal line in the engine bay that comes from the vapor tank into the t-connector that the carbon canister's vacuum actuator outlet ordinarily would plug into?  The vapors would still be going into the intake manifold, just through a different opening.

This would create a large vacuum leak.  It might even overpower the valve in the gas cap and pull a vacuum on your tank.  That would be bad.  If the seal in your canister cap is bad you might have a vacuum leak anyway.  Might partially explain your "lean" problems.

You could just block the line completely and get a two way vented gas cap.  Maybe.  Gas caps are hard to find.  Although the seal on mine was destroyed and it was two-way anyway.  Move the smell to the outside back of the car.  Like the old days.

[chaseincats]

Just now, Zed Head said:

This would create a large vacuum leak.  It might even overpower the valve in the gas cap and pull a vacuum on your tank.  That would be bad.  If the seal in your canister cap is bad you might have a vacuum leak anyway.  Might partially explain your "lean" problems.

You could just block the line completely and get a two way vented gas cap.  Maybe.  Gas caps are hard to find.  Although the seal on mine was destroyed and it was two-way anyway.  Move the smell to the outside back of the car.  Like the old days.

Doesn't having the carbon canister connected properly create a semi-vacuum leak?  The seal is indeed bad in the vacuum portion of the canister.

[Yarb]

You can smell gas regardless of where it’s coming from IMO.

[Zed Head]

Probably won't fit but it shows the concept.  The old days when "PCV" was a tube that exited to the roadway from the valve cover.

https://www.tanksinc.com/index.cfm/page/ptype=product/product_id=638/mode=prod/prd638.htm

 

[Yarb]

Go look at Dave’s Post. Eliminate that and go from there.

[Zed Head]

2 minutes ago, chaseincats said:

Doesn't having the carbon canister connected properly create a semi-vacuum leak?  The seal is indeed bad in the vacuum portion of the canister.

It's a controlled leak.  A small one that is only open when the eninge is off-idle.  The vacuum control hose is on a "ported" vacuum souce on the throttle body.

[chaseincats]

Just now, Zed Head said:

Probably won't fit but it shows the concept.  The old days when "PCV" was a tube that exited to the roadway from the valve cover.

https://www.tanksinc.com/index.cfm/page/ptype=product/product_id=638/mode=prod/prd638.htm

 

I'm trying to eliminate all gas smell both in and outside the cabin

[chaseincats]

Just now, Zed Head said:

It's a controlled leak.  A small one that is only open when the eninge is off-idle.  The vacuum control hose is on a "ported" vacuum souce on the throttle body.

Right, so why wouldn't plugging the metal tank line into the ported line that goes into the throttlebody work?

[chaseincats]

1 minute ago, Yarb said:

Go look at Dave’s Post. Eliminate that and go from there.

Do you know how long ago that thread was?  That might be tough to find

[Zed Head]

18 minutes ago, Yarb said:

Go to @Dave WM post and see how he found one I believe off of an older pathfinder that worked. You may find that your issue is back at the tank. There’s a check valve in place back there as well.

If Dave WM has found a canister from a newer vehicle that works that would probably be the simplest most direct way to go.  The concept is the same and Nissan kept stuff that worked around for decades.  My 95 Pathfinder had an AAR valve that was essentially the same as a 1975 280Z's (I think, it's sold now, can't double-check).  Same basic shape and function.

Edited April 1, 2024 by Zed Head

[chaseincats]

1 minute ago, Zed Head said:

If Dave WM has found a canister from a newer vehicle that works that would probably be the simplest most direct way to go.  The concept is the same and Nissan kept stuff that worked around for decades.  My 95 Pathfinder had an AAR valve that was essentially the same as a 1975 280Z's.  Same basic shape and function.

Ah that topic - I believe it was from a mid-90s pathfinder too

[Zed Head]

9 minutes ago, chaseincats said:

Right, so why wouldn't plugging the metal tank line into the ported line that goes into the throttlebody work?

There would be no "control".  You might also flood the intake with vapor as the car sits in the sun.  Vaporization and condensation.  Engineers spent a lot of time and effort trying to figure out how to handle the vapors in a way that solves and avoids problems.  I'm sure that there are people out here who've tried to outthink the engineers and ended up back at their solution after going around in circles.

The charcoal canister and its control system is really simple.  The hardest part of the Pathfinder mod is probably mounting the canister.