Hi Please help with fuel line and vent lines on 1971 FWB thank you

[Brett Moore]

Hello,

How many of the vent lines are actually needed on a 1971 Fleetwood Brougham?  After changing the frame we ran all new lines, including a stainless fuel line we bent to fit from inline tube.

But we did notice that the fuel tank actually has a total of 5 lines. Two lines come off the sender and three come right from the front of the tank How many are actually needed?  Are some needed to vent or can we just weld up the ones we don't need?

Could a previous owner have possibly put in an EFI tank with return lines at some point?

I would ideally like to keep this as simple as can be- which is one nice new stainless fuel line from the tank to the fuel filter on the carb.

Thank you so much,

Brett Moore

[Scot Minesinger]

There are a bunch of vent lines and all.  Make sure at a minimum you have of course the supply and return.  I think that they could be on opposite sides, not sure.  I would replace the other lines as per how it was done at the factory.  If the frame is off, there is no time like now.  You will always regret later when car is all back together and you went to all this trouble.  I know that there is at least three steel lines front back, and one is vent to canister.  Then there are a bunch of other lines local to back of tank area.  This is all diagrammed in shop manual. 

I just replaced the rubber fuel lines on a 72 Eldorado, and there are quite a few rubber lines in back.  This car was remarkably rust free and so we did not change the steel fuel lines.  It became simplified by 76 or earlier.

["Cadillac Kid" Greg Surfas 15364]

Brett,
If you haven't gotten a copy of the factory service manual I would highly recommend you do so.
the fuel tank connects are as follows;
1:fuel pick up/sender- fuel line (to fuel pump) and vapor return line from pump.
2.there are 3 "vent " connections at the front of the tank. They go to the 3 hose connection of the vapor separator located above the rear axle  in just the same order they are on the tank.
3. The fourth connection on the liquid/vapor separator is for the hose to the charcoal cannister in the engine compartment.
Greg Surfas

[Scot Minesinger]

Greg highly recommended the purchase of a shop manual and I hinted at it, but I would like to amend my post.  I very strongly recommend you get a shop manual also-should have been more clear about that.  It is the best $30 ever spent on my car.  They are commonly sold on e-bay for $35 or so.  Then you should follow it closely whenever you can except for a few minor accepted collector/driver deviations.  The fuel and brake systems are not one of the areas departed from by most people enjoying these cars.

[Brett Moore]

Thank you everyone. I actually have two shop manuals.  Just moved (hard to do with such a project underway but still feasible) and they are in boxes.

I'm leaning towards returning the fuel system to stock.  I assume that the multiple lines and fuel separator are to avoid vapor lock and improve driveability.  Is that correct?

How about the return from the fuel pump.  Any thoughts on the theory behind the operation?  I am curious.

The original lines are long gone so I will be constructing them from scratch.  Does anyone know if the return line from the fuel pump to the tank and the vapor canister line are steel or rubber?  Any idea what the ideal size line should be?  Thanks in advance!

With the tank out I am going to treat it with the Hirsch kit and clean and paint the outside.  Should I do anything with the sender?  It works...leave it alone, I assume?

Thanks again!
Brett Moore

[Scot Minesinger]

The return front to back line prevents vapor lock.  The fuel pump brings in more fuel than can be used most of the time so fuel will be pumped in large enough volume to not heat up and vapor lock, and the access is returned to the tank.

The supply front to back of course is the most vital.

The other front to back line is essentially a vent line so that gas vapors do not leave the tank and pollute.  That line terminates at the canister and then the canister is piped to carb.

Highly recommend returning to stock 

[TJ Hopland]

So does this have the typical 3 lines front to back 3/8 5/16 1/4 and the odd separator that adapts to the 5 lines to the tank?  Why 5 lines to the tank?  I can't quite grasp what they were thinking there.  Obviously must not have worked that well since it was a 1 or 2 year thing?   

[Scot Minesinger]

There are three lines front to back the way I read this post (and on a 72, 74, 75 and 76 Cadillac (did not work on a 71 or 73 yet)), but at the tank there is a spaghetti network at the filter unit above axle.  By 73 or certainly by 74 this was simplified in back.  Yes, last two Cadillacs for me was a 72 FWD and a 76 RWD and replaced the rubber rear fuel lines on both running front to back (plus other and rear ones at tank-local) and the front to back were 1/4", 5/16" and 3/8".

[TJ Hopland]

73 eldo is the 3 lines on the frame to 3 lines on the sending unit just like pretty much every GM from the era I have tangled with.  NEver seen one with this separator thing before.   The couple 71-72's I have worked on recent enough to remember were commercial chassis so maybe those were different than the regular production cars. 

["Cadillac Kid" Greg Surfas 15364]

TJ,
The vapor/liquid separator is located back at the tank. It is mounted to the body just about over the rear axle and has 3 connections to the tank with the fourth connection to the line from the canister up front.
Greg Surfas

[Brett Moore]

Thanks everyone.

What kind (rubber or stainless, and if stainless, what size) of fuel line should I buy for the return (fuel pump back to tank) and separator to charcoal canister?

Thanks in advance,

Brett Moore

[Brett Moore]

Hi everyone,  I wasn't sure if you saw this but I was hoping someone could help me out with the correct size for the fuel return lines from the pump to the tank and the charcoal canister to the tank.  I think I have someone who can bend and flare the lines but I would like to furnish him with stainless lines from inline tube.

He can get steel lines from the local parts store and I am sure they are ok but after going through this much trouble I would prefer to have stainless and the cost differential really isn't that much anyway.

Thanks again,

Brett

[beastly beauties]

I know I am responding late to this, but my advice would be to purchase the prebent stainless lines from Inline Tube. I used these and they fit great, well worth the price, and I will never have to replace them again. I found several new sending units online and also recommend spending that $100.00, rather than the "PIA" replacing later on. You say you replaced the chassis. If the body is still off than I would not even question changing all your fluid lines to the prebent Inline Tube ones. You are at a huge advantage at not having the body in the way. Don't cheap out now. Don't forget to place a little Vaseline on the fuel sender float so it won't stick fast to the gas tank bottom with the fresh sealer applied, which takes a while to properly cure. Good luck, D. Symonds

[Brett Moore]

The body is back on the frame already but that's ok. It was changed at a body shop and not a restoration shop which is why I need to track down and sort some loose ends...but I do think that this is it and I'm on the home stretch here.

Inline tube doesn't list pre-bent lines for a Fleetwood. Just for a Deville and Eldo. Should I risk asking them to make the Deville lines 'longer', or just buy raw unbent line and have an old car friendly shop bend and flare to match the car?

Also I didn't see any Caddy fuel level senders on the site, just Chevy. Any idea where I can get s new one of high quality that will work?  (I have had a lot of problems with some questionable aftermarket parts.)

Thanks again and happy 7/4.

[NORTHPORTGUY]

maybe i am in the right place...not well acquainted with how the forum works..

in any case my my 71  eldo charcoal canister. i do not understand how to replace the filter paper on the bottom.. or for that matter the charcoal inside.  It strikes me as a rather useless device but I'd like my engine to be as functional as practical   S[o  How do you unscrew or otherwise disassemble  the stupid thing?  [/b]

Ken Wiebke

["Cadillac Kid" Greg Surfas 15364]

Ken,
I would suggest you start a new topic in this section of the forum titled something like"charcoal cannisters".
Greg Surfas

[Brett Moore]

Hey folks,

So the car is at an old car friendly shop that is capable of bending and flaring the lines.  It turns out the sender I had in the car was not original and missing one of the connections. We can't run the lines in the identical location to stock, as the body would have to be separated from the frame again and I don't want to go there.  I'm not looking for 100 points, I just want to keep this fine Caddy on the road a long long time and the newly powder coated frame will help me do just that.

We are stuck on the charcoal canister. Where does it go?  How do the mounts work?  We have the shop manuals but they are not providing the necessary detail.  Anyone have any thoughts, or better yet, a pic?

Thanks in advance,
Brett

[Scot Minesinger]

Brett,

You should be able to install the fuel lines in same path as original without separating body from frame with a few double flare splices.  I just did this on a 1970 Cadillac and had two splices in each line without separating body from frame.  The fuel line routing provides for great protection and highly recommend using the original layout.  Obviously the fewer splices the better.  Don't replace steel sections with rubber - often I see that.