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My '68 came with a wasted sending unit and internally pretty rusty (although not original) fuel tank. Eventually I decided to replace it and pulled it a couple of weeks ago. Had been anxiously waiting for the new tank to get that chore completed, but realized upon opening the box that they're not all the same. The tank in the car had had the return line plugged. It looked like maybe they had brazed a brass plug into it and painted over it. Anyway, the new tank has the return port on it but I don't have a return line, which I'm assuming also means I don't have a fuel pump with a return port on it. A lot of what I'm assuming is normal is just based on what I've read here or elsewhere because I've never worked on one of these before, so please bare with me!
The tank I'm replacing has what appears to be a mechanical vent on it, but the new one does not. I have replaced the gas cap with another vented one. If I plug that return port on the tank am I going to have issues? If not, is there a recommended method for plugging it without worrying about the plug working loose or rotting out in 5 years?
The carb is a replacement Q-Jet (this is still "mostly" an L79 car) in case that matters. Thanks in advance!
Similar on my 68 where the carb and fuel pump had been swapped out rendering the return line unnecessary. Just ended up capping the top port of the tank before putting it in. Vented cap is a must though.
Similar on my 68 where the carb and fuel pump had been swapped out rendering the return line unnecessary. Just ended up capping the top port of the tank before putting it in. Vented cap is a must though.
How did you cap it? A short piece of tubing with a plug and some hose clamps would work, but I fear that they wouldn't work indefinitely and I'd be pulling the tank again in 5 years just to replace the tubing. I've thought about cutting off the flare, threading the tube, and putting a brass compression fitting on there and capping that, but that's about all my imagination has come up with. Unless I can find someone to plug (braze?) it closed somehow.
How did you cap it? A short piece of tubing with a plug and some hose clamps would work, but I fear that they wouldn't work indefinitely and I'd be pulling the tank again in 5 years just to replace the tubing. I've thought about cutting off the flare, threading the tube, and putting a brass compression fitting on there and capping that, but that's about all my imagination has come up with. Unless I can find someone to plug (braze?) it closed somehow.
I just did the same to mine, I bought rubber vacuum caps at Pep Boys and then clamped them. Works fine.
I just did the same to mine, I bought rubber vacuum caps at Pep Boys and then clamped them. Works fine.
I am worried about the fuel resistance (or lack thereof) of the rubber vacuum caps. The vinyl ones look like they are more fuel resistant and would last much longer, but of course I bought rubber ones today. Ordered vinyl ones on Amazon, and I think I'll fill the return tube on the tank with Jb weld before I put the cap on. Redundancy and all that......
Before you start making changes, are you aware that the L79 fuel pump did not have a return line because the return line is coming off the fuel filter. See the sample filter below. If you see a 1/4" return line at the frame rail near the tank and see the other end on the frame rail near the fuel pump, use it, the engine will run better with it.
I was not aware of that, although I really hadn't looked around much up front since I discovered this complication. The return line is not present at the rear of the car, or as far as I can see up the right side frame rail with the tank removed (pretty far, although I don't have a point to reference). It does make me want to see what's up as far as a fuel filter, though.
This car received a frame-off "restoration" in the early 90's and it's unclear what was actually restored vs. just put together with new parts previously. It appears to be the original HT block, but the heads are not original, and neither was the fuel tank, which is what got me into this situation. I will definitely take a look at the fuel pump and filter before I plug that return port on the tank, but I don't see myself replacing that return line for originality's sake. Thanks!
First apologies for the pic size as I'm still working out life post photobucket thumbnail links.
Return line is here under the car. If it's not connected at the pump/filter and your car hasn't had issues then probably no need to connect it up again (if it's even still there). I also understand that not all cars had a return line either and it was dependent on the motor installed.
I plugged my with a simple vinyl vacuum cap that I then just zip tied tight. That was in 2012 and the fuel vapor hasn't deteriorated the cap yet. The gasket for the filler neck is a different story.
The return line was to prevent vapor lock from the high under hood temperatures on our cars. Lou.
Makes sense. Unfortunately I haven't driven this car enough to know if it is prone to it or not. It was trailered from the home of the guy I bought it from to the shop, and I drove it home from the shop and pulled the tank and center gauge cluster (will be replacing the radio). It hasn't moved since I pulled the tank, obviously, so I really don't have a history. I only know that we won't be pulling the body, ever. We're just not equipped to do that.
Hi ST68,
Welcome!
Here's a photo of the fuel supply line from the fuel pump to carb that has the filter and return line that is typical as MW and Lou described.
You can see the smaller diameter return hard line doing a u-turn and running back down from the top of the filter.
Seeing it may be an indication whether any of the rest of the system system is still present..... the hard line on the frame rail for example... and can still be used if you wish.
Regards,
Alan
Always interesting to see new member's cars.... photos?
I should probably get some pics up. Unfortunately the only thing worth showing is what's under the hood. The car is up on jack stands in the barn right now and not very photogenic.
Definitely nothing like that. I have a solid line direct from the fuel pump to the carb. There's no return line and no inline filter.
I finally just decided to cap the return tube on the tank and got the tank in place today. The problem now is getting the straps pulled down far enough to get bolts in. I am beginning to regret replacing the pads.
I should probably get some pics up. Unfortunately the only thing worth showing is what's under the hood. The car is up on jack stands in the barn right now and not very photogenic.
Definitely nothing like that. I have a solid line direct from the fuel pump to the carb. There's no return line and no inline filter.
I finally just decided to cap the return tube on the tank and got the tank in place today. The problem now is getting the straps pulled down far enough to get bolts in. I am beginning to regret replacing the pads.
Look at a picture of a new strap, yours are probably curled up at the end that hooks into the cross support bracket and need to be straightened to look like a new strap would. I just took the tank out of my 69 and had to do that to my straps. T
Let's see if I can manage this....first time posting a pic!
As you can see the fuel line is direct from the pump, no filter. I didn't do the work here so I don't know what configuration this would have been correct in, but it is a pre-formed fuel line.
This thread is a little old,,,, but. I have the same car, 1968 327 350 hp. But a Holley 4175 carb. I have been fighting a, flooded hot start, issue since I got the car. I think I have boiled down the cause to no return line. In your post you said you were going to cap the return line. Did you cap it, and has it been working ok for you? I hope you don't have issues with flooding. I worked on this issue from a carb stand point and didn't solve it yet. I have the GF-432 filter and lines on order and am going to hook up the return line. Crossing my fingers.
This thread is a little old,,,, but. I have the same car, 1968 327 350 hp. But a Holley 4175 carb. I have been fighting a, flooded hot start, issue since I got the car. I think I have boiled down the cause to no return line. In your post you said you were going to cap the return line. Did you cap it, and has it been working ok for you? I hope you don't have issues with flooding. I worked on this issue from a carb stand point and didn't solve it yet. I have the GF-432 filter and lines on order and am going to hook up the return line. Crossing my fingers.
When the Q-jet came off my 6t8 327/ 350 hp the gf432 went away also. Tried using them for awhile but seemed as if the reformulated fuel destroyed them, so the return line was all but forgotten. Never had that issue you have. Quick question; what intake? and what intake gaskets are on the engine. OEM manifolds have an exhaust crossover for HOT exhaust gasses to travel under the carb to warm it up when cold. Problem is that there is no shut off so those hot gasses are always present. Now aftermarket intake gaskets have the capability to block the crossover.T
When the Q-jet came off my 6t8 327/ 350 hp the gf432 went away also. Tried using them for awhile but seemed as if the reformulated fuel destroyed them, so the return line was all but forgotten. Never had that issue you have. Quick question; what intake? and what intake gaskets are on the engine. OEM manifolds have an exhaust crossover for HOT exhaust gasses to travel under the carb to warm it up when cold. Problem is that there is no shut off so those hot gasses are always present. Now aftermarket intake gaskets have the capability to block the crossover.T
I have a stock intake manifold,,,, and a new style gasket that blocks the hot gasses,,,, spacer,,, heat shield ETC. I have eliminated the HOT carb as the cause of my flooding problem. After setting for a bit, put my hand on the front bowl,,, 45* outside temp,,, front bowl luke warm,,, still floods, fuel shooting out of the forward carb vent.
What carb are you using? Did your GF-432 filter have a hold down bracket, and what was it bolted to?
When is the fuel shooting out of the bowl vent? Cranking, just after shutting off,idleing? And flooding? Is fuel dripping into carb? There are a lot of us that can help so please be very specific. Which gasket are you referring to? Intake to carb or intake to heads?
I ran a 4165 spread bore on my 69 350 with no return and no problems with that one either. T
The gf432 came off 2 decades ago maybe someone can come up with a picture.
When is the fuel shooting out of the bowl vent? Cranking, just after shutting off,idleing? And flooding? Is fuel dripping into carb? There are a lot of us that can help so please be very specific. Which gasket are you referring to? Intake to carb or intake to heads?
I ran a 4165 spread bore on my 69 350 with no return and no problems with that one either. T
The gf432 came off 2 decades ago maybe someone can come up with a picture.
Carb to intake gaskets,,,, all 3,,, metal heat shield,, new style gasket,,, and thick phenolic heat gasket. Heat shielding on the fuel lines. After the engine starts is when fuel shoots out of the carb vent, then sputters and quits. New needle,, seats,, floats. There is always fuel dripping on the manifold just below the primary throttle shaft. Fuel line is plumbed directly from the stock fuel pump to the carb,,, no return line.
The gaskets that I was refereeing to were the intake to head. Most Holleys have a plug in the fuel bowl to verify the fuel level, for some reason Holley did not use them on the spread bores which means that you have to set the fuel level by adjusting the float via a measurement. Are you sure that your adjustment is spot on? To high of a fuel level could cause the squirt out the vent upon start-up. A bad power valve will cause an internal leak in the carb, you will see the throttle plates wet and gas sitting on top of throttle plates will seep out the throttle shaft. I haven't seen that you have verified the fuel pump pressure. If memory serves me correctly it's supposed to be 4 to 5 psi. Another possibility is that the metering block in the carb is defective [unlikely]. Does the fuel coming out of the vent happen on cold starts or just on warm restarts? T
03-03-2018, 06:23 PM
New fuel tank complication....
