| Author | Message | ||
| Bill Sebestyen (Bill308)
Junior Member Username: Bill308 Post Number: 186 Registered: 5-2001 |
Thanks Magoo and Steve. It looks like we all agree that the max flow direction should be toward the vapor separator. | ||
| magoo (Magoo)
Advanced Member Username: Magoo Post Number: 2580 Registered: 2-2001 |
Bill I am sorry I goofed, It was late last night when I checked the valve and it was hard to read. So today I removed the valve from the fire wall at the expansion tank and the "made in Italy" end which is tapered like yours definetly plugs into the hose coming FROM the cannister. | ||
| Bill Sebestyen (Bill308)
Junior Member Username: Bill308 Post Number: 185 Registered: 5-2001 |
Steve and Magoo, The way I interpret Magoo's last post, � P.S. The made in Italy side is on the top of the hose "AWAY" from the cannister and going under the 1/4 panel. The Italy side does not connect to the hose from the cannister. The other tapered stem side connects to the cannister hose.�, his 2-way valve is oriented with the flat (tapered?) side toward the charcoal canister, but maybe I�m interrupting this statement incorrectly. | ||
| Bill Sebestyen (Bill308)
Junior Member Username: Bill308 Post Number: 184 Registered: 5-2001 |
Steve, I was unable to detect an opening vacuum threshold using my Mityvac. This was confirmed by alternately sucking on both ends of the valve. I have two examples of this valve and both respond the same way. The difference can best be described as a difference in flow rate or restriction to flow. Flow towards the flat side is several times the flow toward the �Made in Italy� side, for a constant vacuum. | ||
| Steve Magnusson (91tr)
Member Username: 91tr Post Number: 688 Registered: 1-2001 |
Bill -- my ex-'78 assembly notes match magoo's description: flat side up on firewall (max flow direction connected to fuel/vapor separator) cone side down (connected to charcoal canister) I think you're right though that it would make sense to have the 2-way valve designed so that, if the fuel tanks get significantly overpressurized, it allows slow venting to the charcoal canister yet for pressure differentials in the range of expected engine operation the minimum flow direction is completely closed. You've got the valve -- is the min flow direction just always open, or is there a minimum cracking pressure? | ||
| magoo (Magoo)
Advanced Member Username: Magoo Post Number: 2575 Registered: 2-2001 |
P.S. The made in Italy side is on the top of the hose "AWAY" from the cannister and going under the 1/4 panel. The Italy side does not connect to the hose from the cannister. The other tapered stem side connects to the cannister hose. | ||
| magoo (Magoo)
Advanced Member Username: Magoo Post Number: 2574 Registered: 2-2001 |
Bill, On my 79 308 GTS the bottom of that valve which is the funnel looking or tapered end is in line "FROM" the connection at the bottom of the charcoal cannister. In other words the hose runs from the bottom of the cannister up to the funnel, tapered end of the valve,which is bolted to the rear firewall next to the luggage compt. at the expansion tank and connects. The other part of the hose connects on to the more flat side of the valve and continues on around the expansion tank and goes under the rt. rear 1/4 panel. | ||
| Bill Sebestyen (Bill308)
Junior Member Username: Bill308 Post Number: 183 Registered: 5-2001 |
Thanks Steve, your comment is consistent with my thoughts. You sent me an email some time back, with drawings showing flow directions for this system. One of your drawings, labeled "Engine Running", had the 2-way valve X'd out and arrows pointing toward the fuel/vapor separator, seeming to imply no flow in this direction. The problem I have is that my (yours previously and its getting a lot of use) OM implies that vapors from the tank are stored in the charcoal canister under some conditions. This description requires some flow from the fuel/vapor separator toward the charcoal canister. Perhaps what this means is, if vapor pressure builds up in the tank, it will bleed past the 2-way valve and be absorbed in the charcoal canister. The implication is that this is the minor flow direction and the major flow direction is toward the fuel/vapor separator to prevent collapse of the tanks. Could you take another look and let me know what you think? | ||
| Steve Magnusson (91tr)
Member Username: 91tr Post Number: 685 Registered: 1-2001 |
Bill -- I'm 99% sure that the max flow direction should be towards the fuel separator (i.e., the valve's function is to allow air to flow easily into the gas tanks, yet prevents air from being drawn out of the gas tanks by the vacuum placed on the charcoal canister (avoiding potential collapse). My information on the subject is at work so I'll recheck tomorrow. | ||
| Bill Sebestyen (Bill308)
Junior Member Username: Bill308 Post Number: 182 Registered: 5-2001 |
To all, please disregard the redundant thread on this subject and Rob, if you could delete it, that would be great. It seems I�m better at responding to a thread than starting one. I tried to insert a drawing of the evaporative emissions system in the last post, but it was too big. After much thought, I believe the max flow direction should be toward the fuel/vapor separator and fuel tank. To put it all in context, I�m posting the following drawing from my Parts Catalog. If anyone can confirm this is the correct orientation I�d grateful.  | ||
| Bill Sebestyen (Bill308)
Junior Member Username: Bill308 Post Number: 181 Registered: 5-2001 |
Sorry, missed the "Upload Attachment button", one more try. I need help to orient the 2-way valve on my 1978 308 gts. This valve is part of the evaporative emission control system and was not present when I purchased the car. I'm installing it for the first time. It is fitted in the vapor line running between the fuel/vapor separator, which is plumbed to the right side fuel tank, and the charcoal canister. The location of this valve is on the engine side of the trunk wall, probably below the coolant expansion tank. The valve flows more in one direction, away from the, "Made in Italy Side" (or convex side) toward the flat side, and looks like this:  According to my owners manual, this valve has two functions: - slight tanks pressurization - air inlet into tanks to prevent any possible vacuum An extract from the general discription in the owners manual says, "The release of fuel vapors from the fuel tanks into the atmosphere is prevented by a proper system through which the vapors are conveyed to an activated carbon trap in engine compartment where they are abosorbed." |