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10/15/12 12:59pm - Original Message: 'Gas tank/fuel line problem??'
danascar
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. 1999 Covertible, 6 speed, Atomic orange, Oak interior

Joined: 1/28/2010
Posts: 763
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. Ouch  

|UPDATED|10/15/2012 10:59:08 AM (AZT)|/UPDATED|


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Dan T
 

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10/15/12 3:05pm - Reply: 'Re: Gas tank/fuel line problem??'
F4Gary Gold Member
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Grapevine, TX - USA

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1972 LT-1 convertible with factory air.

Joined: 8/26/2006
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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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10/15/12 3:27pm - Reply: 'Re: Gas tank/fuel line problem??'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

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#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

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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......

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Joel Adams
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10/15/12 5:59pm - Reply: 'Re: Gas tank/fuel line problem??'
Redwingvette Lifetime Member
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Waterford, MI - USA

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1973 Red coupe

Joined: 9/13/2002
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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.

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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, F-body seatbelts, Pioneer CD player
Magnaflow Exhuast System
Dewitt radiator and dual electric fans
Borgeson Steering box
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10/16/12 5:05pm - Reply: 'Re: Gas tank/fuel line problem??'
danascar
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. 1999 Covertible, 6 speed, Atomic orange, Oak interior

Joined: 1/28/2010
Posts: 763
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.


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10/16/12 8:41pm - Reply: 'Re: Gas tank/fuel line problem??'
Redwingvette Lifetime Member
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Waterford, MI - USA

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1973 Red coupe

Joined: 9/13/2002
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That is the part.

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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, F-body seatbelts, Pioneer CD player
Magnaflow Exhuast System
Dewitt radiator and dual electric fans
Borgeson Steering box
Click here for Brian's Home Page 



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10/16/12 9:28pm - Reply: 'Re: Gas tank/fuel line problem??'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

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

Joined: 11/8/2003
Posts: 19454
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....

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Joel Adams
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10/17/12 8:16am - Reply: 'Re: Gas tank/fuel line problem??'
Jaws79 Lifetime Member
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Sykesville, MD - USA

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1979 Corvette Coupe Corvette Light Blue Midnight Blue interior Mirrored Glass T-tops

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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!).
 
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10/17/12 11:42am - Reply: 'Re: Gas tank/fuel line problem??'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

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

Joined: 11/8/2003
Posts: 19454
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....Geek
The cars after '74-5 also had the bladders in the tanks, so that prolly has something to do with it, too.


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Joel Adams
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             NCRS

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10/17/12 1:45pm - Reply: 'Re: Gas tank/fuel line problem??'
danascar
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. 1999 Covertible, 6 speed, Atomic orange, Oak interior

Joined: 1/28/2010
Posts: 763
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....Geek
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.

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10/18/12 8:11am - Reply: 'Re: Gas tank/fuel line problem??'
Jaws79 Lifetime Member
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Sykesville, MD - USA

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1979 Corvette Coupe Corvette Light Blue Midnight Blue interior Mirrored Glass T-tops

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Maybe one less thing to worry about!
 
Barry
 
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4/1/13 9:39pm - Reply: 'Re: Gas tank/fuel line problem??'
danascar
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Germansville, PA - USA

Vette(s):
1974 Coupe 358ci 4 speed Black w/Medium Saddle interior w/79 custom leather seats. 1999 Covertible, 6 speed, Atomic orange, Oak interior

Joined: 1/28/2010
Posts: 763
Well after getting most all the suspension upgrades done I finally got around to tackling the separator valve replacement. Found it and immediately saw that the larger of the 2 hoses running to valve, the one from top of the tank was split open just below the clamp on the valve. Can this hose be replaced without dropping the gas tank? Don't really want to do that if I don't have to. Can it be accessed from tank filler area if rubber seal is removed, and how is that done? Valve actually looked good but I will replace that just to prevent future problems.(I did epoxy the seams) Service manual amd assembly manual really doesn't show much of anything on this Unhappy There is enough slack in hose to cut bad part off and reattach but I'd like to do it correcty.
 
After working on it all afternoon I finally got the offending hose off. Had to drop spare tire, and carrier, unbolt straps, and slide tank as far right and forward as possible. This gave enough room to get my hand on the hose and spring clamp. Had to squeeze spring clamp blindly but got it off and removed hose. Good thing I did because hose on tank end was also cracked.
And so tomorrow it goes all back together again...Clap

|UPDATED|4/1/2013 7:39:08 PM (AZT)|/UPDATED|


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Dan T
 

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4/1/13 11:47am - Reply: 'Re: Gas tank/fuel line problem??'
rraider1
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Woodland, WA - USA

Vette(s):
1977 T-Top,350,Auto Black Ruby Pearl,Steeroids R&P conversion

Joined: 10/14/2003
Posts: 1152
this diagram might help
 


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Bob R
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4/1/13 9:41pm - Reply: 'Re: Gas tank/fuel line problem??'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

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

Joined: 11/8/2003
Posts: 19454
The hose can be changed without pulling the tank. You will need to remove the vapor separator, tho. The hoses should have spring clamps on them, unless they have been changed to the worm/screw type. It's a tight fit up in there, past the mufflers, but it can be done. 

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Joel Adams
C3VR Lifetime Member #56    
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             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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