Peter Zimmermann

...remove the gas cap, find the pictured vent tube, and tell me what it connects to.



If the line goes into the tunnel, please find its other end and tell me what it connects to in the engine compartment. If it goes to a charcoal cannister...

Thank you for any help that you can offer!

Jay Gratton

Romanowski will check this out for you when he gets home from work today. I would, but my car is an hour away in storage.

Peter Zimmermann

Thanks, guys. I need to know what line hooks to it, because I have to take the assembly back off of the tank in order to open up the hose nipple, and put the cap assembly back on. I'm wondering if some of the running problem (yes, I'm looking for that needle in a haystack) is being caused by the tank not being vented (of course, it might vent past the filler cap as well). Before I begin diagnosing the computer, injectors, etc., I'm trying to make sure that all the little issues that "might" be a problem are corrected.

It doesn't help that just about every AFC engine compartment picture in my Haynes and Clymer manuals is different (component layout, etc.) from my mess. I'm now in the process of deleting the home made decel valve set-up done by someone along the way, and after that I should have my new air intake that connects the AFM to the throttle body (currently on order).

Matt Romanowski

Mine is capped, but I believe it goes to the charcoal canister. Almost positve. Venting it to the atmosphere would do the same.

Yes, it could cause a running problem, but not much.

Peter Zimmermann

Matt, from your experience, is the gas cap, which feels spring-loaded, sufficient to "vent" the tank without running issues? I'm sorry to bug you with this, but my car has so many problems that I never dreamed that I would be chasing down issues like this. In the old days, when I maintained a small number of 914s, we never came across stuff like this because all of the cars were actually pretty nice, and well-maintained. There was no need to explore and remember various systems (charcoal cannister, fuel tank expansion chamber, etc.) because points, plugs, valve adjustments, oil return tube o-rings, and an occasional relay or injection part fixed 99% of the problems. This car is really testing me, thanks for your help.

Matt Romanowski

I think the venting from the gas cap alone is probably not enough to run a full tank, but on a short run it's ok. I'm positive the line when to the canister. I would say either put it to the canister or vent it out the bottom of the car with the brake overlow.

racer

I don't recall my '70 having a charcoal canister and on my '76 it was removed. I'd just vent it out the bottom of the car.

skl

I'm pretty sure it is a clear plastic tube that just runs down by the panel covering the master cylinder and vents to the great outdoors...but we have a blizzard outside right now and I'm not walking 150 yards to my shop to look!!! Sorry....

Jay Gratton

I knew Matt would help!

Peter Zimmermann

SUCCESS! Almost, anyway. I started a thread on 914World, and some diagram info was posted. I had never considered that some '74s, and later models, had the charcoal cannister in the engine compartment, not the front trunk (which would explain not having access holes for the 13mm hoses)! Putting it there will allow easy hook-up of the hoses to the fan shroud and air cleaner, and it will let me use the 5mm factory vapor line in the tunnel!

Now all that remains is to learn how to hook up the two hose connections on the expansion tank (which connection is used for the tunnel line, and which is used to connect the the tank vent below the filler cap)? The right side (outboard) hose bib is on the bottom of the expansion tank, but the left side hose bib is on the top of the expansion tank - there must be a reason for that.

BTW; yes, I will open up the pinched-off hose bib pictured in the OP.