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Had a scary occurance yesterday on the way home from Ocean City. Stopped to fill up the tank and then went a few blocks away for a bathroom break (restrooms out of order). Parked the car on a slight up hill spot and got out to go into restroom. Looked down and noticed large puddle of liquid at left rear (drivers side) of car and a steady, almost stream of gas leaking on the drivers side muffler. Checked gas cap and saw gas was slightly below top of filler hole in tank. Immediately moved car to level spot and leak gradually slowed to a stop. Drove home the rest of the way and didn't notice any more leaking. Can the tanks on a 74 leak if filled too high or is there a leak in the tank somewhere up high and to the rear. I would assume the tank should be totally sealed other than filler. Any lines on the left side of tank? Line to fuel pump runs up right side of car. 
|UPDATED|10/15/2012 10:59:08 AM (AZT)|/UPDATED|
|UPDATED|10/15/2012 10:59:08 AM (AZT)|/UPDATED|
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DanT
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On my 72, the vent lines from the charcoal canister return to the driver side top end of the tank. Maybe one of the rubber hoses that connect the tube to the tank is cracked.
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22714
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
There is a vapor separator there on the driver side/top of the tank. You have a semi short hose from the tank nipple to the separator, and then the hose from the charcoal canister, as Gary mentioned. The vapor separator is plastic, two pieces that are glued together. Your leak could be from either of the hoses, or the separator itself. It is waaaaay up in there, but you can fell it with your hand, if you can wrap your arm around the muffler. The separator is held to the tank with two screws....I think mine are 5/16 hex-head, but it's been a while since I been up in there. Mine leaks too....still. It ONLY leaks with a full tank, and it runs right on top of the muffler....no safety issue there, right? I have actually replaced the separator on mine before, to solve the same leak, but it is leaking again. I just haven't taken the time to check and see if it is a hose, or the dang vapor separator itself......
Joel Adams
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I changed both the hoses and the separator on my a while back. My leak showed up when I was doing some work on the passenger side and had the car at a pretty good angle. Funny thing is that the new separator leaked too so I had to seal it before I could install it. It is molded out of nylon so epoxy works well on it. I had to drop the exhaust and mufflers on the driver side to be able to reach the valve and hoses. The separator valve has a float inside of it and is suppose to stop liquids from getting into the charcoal canister from folks that overfill the tanks. Rule of thumb is not to top-off the tanks. Always leave it a little room at the top.
Brian - NCM Lifetime Member
73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, Seatbelt Plus 3point seatbelts, Pioneer CD player
Magnaflow Exhuast System
Dewitt radiator and dual electric fans
Borgeson Steering box
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http://www.fullthrottlecorvette.com/1970--1974-Corvette-Fuel-Tank-EEC-Valve_p_2468.html
I presume this is the separator valve previously mentioned. Best price I could find.
I presume this is the separator valve previously mentioned. Best price I could find.
DanT
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That is the part.
Brian - NCM Lifetime Member
73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, Seatbelt Plus 3point seatbelts, Pioneer CD player
Magnaflow Exhuast System
Dewitt radiator and dual electric fans
Borgeson Steering box
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22714
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Yeppers....that be it. I would take a look first, to see if it is just one of the hoses, rather than spend $40, and then not need it. If you do get a "new" one, I would do as Brian did on his, and epoxy around the dang seam on it....cause it WILL leak, eventually. My replacement one did, just as Brian's did....
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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Does that mean my 79 doesn't have one, or is it just a different part? Mine doesn't leak, even when I overfill it (guess I shouldn't have said anything, I'll jinx myself!).
Barry
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22714
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
I think '74 was the last year for this particular set-up. I think after that, the vapor separator was part of the charcoal canister/purge valve, and the hose from that just runs directly into the top of the tank, with a check-valve....I could be wrong. I should prolly do a little research on that....now you got me curious....
The cars after '74-5 also had the bladders in the tanks, so that prolly has something to do with it, too.
The cars after '74-5 also had the bladders in the tanks, so that prolly has something to do with it, too.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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Adams' Apple said: I think '74 was the last year for this particular set-up. I think after that, the vapor separator was part of the charcoal canister/purge valve, and the hose from that just runs directly into the top of the tank, with a check-valve....I could be wrong. I should prolly do a little research on that....now you got me curious....
The cars after '74-5 also had the bladders in the tanks, so that prolly has something to do with it, too.
The cars after '74-5 also had the bladders in the tanks, so that prolly has something to do with it, too.
All my research for them only turned up the valve in the link for just 1970 to 1974.
DanT
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in Forum: C3 HVAC, Fuel, Emissions, and Exhaust
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