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#1
10-23-2023, 04:49 PM
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Fuel tank venting
If you use a vented gas cap, can you plug the gas tank vent nipples? my tank has 3.
I ran a rollover valve from one nipple and its up high and verticle but to avoid the exhaust pipes I had it ran incorrectly (unbeknownst to me) and it traps some fuel in the line. got under to change the diff gear lube and noticed fuel had purged out the vent valve. quickly realized why. the way the exhaust is, can't find a way to run the line up right out of the tank nipple, to close to the exhaust. I had ran line horizontal then up. so looking for an alternative. |
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#2
10-23-2023, 06:11 PM
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original part vent
.....I still have this original piece. can the vent line be ran to one of the tubes and vent that way?
Last edited by JUDGE3; 12-20-2023 at 10:51 AM. |
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#3
10-23-2023, 07:44 PM
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Vented gas caps are vented in,not out.Tom
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#4
10-23-2023, 08:14 PM
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Without a vented (IN) gas tank, the gas tank would collapse over time(atmospheric pressure.
The Ford Emissions guys in Allen Park Mi occasionally forgot to remove the cap when draining (sucking) out fuel in the tank before a test. The tank would be the size of a 64 GTO drivers side seat afterward. Time to install a new tank. The vent can only pass so much airflow in a minute. Triple the suction (vs normal) and the tank caves in. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
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#5
10-23-2023, 08:44 PM
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Quote:
That's what the liquid/vapor separator you have there is designed to do. The three vent nipples from the tank hook up to it, and the fourth line off of it runs up to the carbon canister in the engine compartment. The three tank vents are designed so that regardless of how the car is parked (uphill/downhill/leaning) one of the vents is always open to vent (out) the tank without fuel overflow. I would advise hooking them all back up. Hope that helps. 
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Eric "Todd" Mitten '74 Bonneville 4dr Sedan (455/TH400/2.93 open) '72 LeMans GT (455/M-13/3.23 [8.5"] posi) '71 GTO Hardtop (400/TH400/3.07 12 bolt posi) ‘71 GTO Convertible (455HO/TH400/3.23 posi) '67 GTO Coupe (455/ST-10/2.93 posi) '67 Tempest Wagon (428/TH400/2.56 posi) Deuteronomy 8:3 
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#6
10-23-2023, 11:04 PM
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As a kid my mom lost the gas cap on our 66 Catalina. Bought one at a Texaco station, gas tank collapsed.
They had to get us a new tank and finding a station wagon tank was not easy. |
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#7
10-24-2023, 09:23 AM
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holes in cap?
I see some drilled 3 small holes in the gas cap. that achieved vent in/out.
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