Brake/Fuel line overhaul

[MYBAD79]

The Summit rubber hoses are "supposed to" be good for fuel... mine are almost 5 years old and so far so good... dunno if the teflon hose is better, thought Dupont had a patent on TPFE (or is it PTFE) ... teflon ... and on using that name. I thought there was some stink with the SLick50 guys about Teflon in their product...

anyways... the vapor line? Mine was rusted and fell off the frame rail one day I put my hand up there.... cut it and crimped the end of the line about 2' from the tank, the opening is now very very small... done...

I also have a vented gas cap. I have not have any issues with fumes in the garage and that's in a hot central FL garage. I never fill the tank all the way, usually 3/4 full at the most... maybe that helps, not sure....

 

[denpo]

As I wrote before, I had a WTF moment when I realized that in my vette in her soon-gone form, the fuel return line is not connected on the engine side.
First searched for infos, AIM and Haynes are pretty vague, but from what I understand the return line should be connected somewhere at the bottom of the pump. Problem is, I've checked the pump, and I could not find any plugged holes.



What should I do?

 

[damoroso]

The return line is used with a pump that's set up for it. It would have a return fitting on it. I'm not exactly sure what the bennefit is over the non return line set up (emissions?), but obviously you can run without it.

If you choose to continue without using the return, you might want to consider plugging the return line. It's a direct vent to the fuel tank, letting vapors into the engine compartment. If you do that, there'll have to be some way to vent the tank, either through a vented cap or, as in my case through the vapor canister.

This is a fuel pump for a return line set up:

This is what I did for my system:

You can see where I plugged the return line here:

Incidentally, I've recently learned using a liquid filled fuel pressure gauge under the hood isn't a good idea. As temps in the engine compartment rise, the viscosity of the oil in the guage changes and so does your pressure reading. And reading pressures as low as 0-15psi, that can make for a real accuracy problem!!! So, now I'm replacing this gauge with a non filled one...

 

[MYBAD79]

Some pumps don't have a return line connection, f.e. my Holley pump....

search for my "fuel line nightmare" threads.... there's part 1 and 2....

Here's a photo of what I did to make it work:



From the pump I run a line up to the regulator (which is not more than a "T"). From the regulator the 6AN line runs to the carb, another 6AN line (on the left) is the return line.
Now, this does not work if the carb supply and return is the same size line. I plugged the AN fitting on the return line and drilled a small hole in the plug, I think I used a 1/8" drill bit....

It took me a while to get there but now it all works fine - since my most recent oil change a few weeks ago I put over 500 miles on the '79

 

[Arthur Brown]

it works without return line? Wouldn't the pump supply more fuel than the carburetor needs ?

 

[damoroso]

Yep, the pumps designed to work without a return line, pump to pressure and stop there, there's internal "bypass" valving.

Here's the other end of my system. I'll be adding an inline filter later this week. Karsten chose to use the return, I didn't. It would be easy as the regulator has another out on the other side. Again, I'm not sure what the value added is to running it, especially if you're running a pressure regulator, though braided line certainly adds "cool factor" IMHO.

As for braided line, I found a local supplier who sells the line and fittings, and will also cut the line for you free of charge. Those nice clean cuts only take seconds (with the right equipment) and then it only takes seconds to put the fittings on! I'd suspect any shop who makes hoses could do the cuts for you, and likely wouldn't charge much if anything.

 

[big2bird]

The return line was added in later years to help with vapor lock.
The earlier BBC cars with A/C had a return line from the fuel filter.
Later cars moved it to the pump. I would change the pump, and reinstall the return line.
However, in colder climates, this is probably not an issue.
Install a hard steel line from pump to carb. Buy an extra piece of 3/8" brake line, and practice bending. It's not that hard to do.

 

[keywestjack]

I used stainless braided hose for fuel supply and return. It's easy to install with the body on the frame and should last quiet a few years... system pressure is low so there's no huge potential for leaks - at least between tank and pump... between pump and carb I used AN fittings....

The brake lines are available in stainlesstubing, pre-bent and actually a very good fit. I got mine from MidAmerica back in 2004... $150 if I remember correctly, plus the 4 hoses...

So from the fuel tank to the pump you used braided. Did you use a hose clamp at the tank and pump? Definitely sounds like a good way to go. I just don't want to do another body removal.

 

[MYBAD79]

I used stainless braided hose for fuel supply and return. It's easy to install with the body on the frame and should last quiet a few years... system pressure is low so there's no huge potential for leaks - at least between tank and pump... between pump and carb I used AN fittings....

The brake lines are available in stainlesstubing, pre-bent and actually a very good fit. I got mine from MidAmerica back in 2004... $150 if I remember correctly, plus the 4 hoses...

So from the fuel tank to the pump you used braided. Did you use a hose clamp at the tank and pump? Definitely sounds like a good way to go. I just don't want to do another body removal.

yes, I carefully removed the braids from the first 1" of the line, wrapped the cut with tape to keep the braids from coming loose and then used a hose clamp on the connection to the pickup.
You cannot use a hose clamp without removing the braids.

 

[keywestjack]

Cool, I think in the long run it beats the solid metal line. May even replace my transmission cooling lines with the stuff. I don't know why but it always seemed to intimidate me.

 

[68/70Vette]

If you're going to order a new gas line, I think it's a good idea to order it with AN fittings so you don't have to use rubber hose and band clamp connections. I ordered a 3/8 SS gas line and vapor return line from In-Line Tube and asked them to install AN fittings to the 3/8 SS gas line, which they did at a minimal cost.

 

[keywestjack]

If you're going to order a new gas line, I think it's a good idea to order it with AN fittings so you don't have to use rubber hose and band clamp connections. I ordered a 3/8 SS gas line and vapor return line from In-Line Tube and asked them to install AN fittings to the 3/8 SS gas line, which they did at a minimal cost.

At the tank end or the pump end?

 

[68/70Vette]

Both ends.

I'll be installing an electric pump near the fuel tank: pump, filter, and then a solid metal (CuNiFer) line to the SS fuel line.

I have a rear mounted fuel pump/filter on my 68. But of course, with the 68 I didn't think ahead when I ordered my gas line so I had to mate to the fuel line with the traditional rubber hose;band clamp technique.

With my 70, which I'm working on now, I wanted an AN fitting just in case I decided to go with fuel injection, and hence a high fuel pump pressure. For money reasons I'll probably end up with a carb though.

I liked the idea of having an AN fitting up front near the engine because just having a rubber hose anywhere near headers doesn't seem like a good idea. On my 68, I did have to use the rubber hose and band clamps, but I covered the rubber hose with fiberglass heat protective tubing (bought from Earls).

 

[damoroso]

Cool, I think in the long run it beats the solid metal line. May even replace my transmission cooling lines with the stuff. I don't know why but it always seemed to intimidate me.

Jack,

The only trick to braided line is to have a really clean cut. Any place that makes hoses can cut it for you. Once you have the clean cut, twist the cap on (make sure the hose goes all the way in to the bottom of the fitting), then use some silicone lube for the male "instert" push it in and tighten it up. BTW, I have used hose clamps on braided line without stripping the braid and it's worked well, but not in pressure applications. For instance, my fuel feed line to the pump is clamped, and there are no leaks.

 

[denpo]

I used 8 AN for supply (1/2") - That's overkill for my engine but it fit the tank outlet pretty good ... pushed it onto the hard line and clamped it down with a SS hose clamp

I used 6 AN for the return, again, it fit the line at the tank

That's strange, I measured my tank line, outlet is 3/8 OD, return and vapor are 1/4 OD. Wouldn't I rather need 6an and 4an an instead of 8an and 6an?

While I'm at it :

-I've seen different filter "size", from 30 microns to 100 microns, which one is adequate for a pump to card filter?
-Is a pump to carb filter enough or should I had a tank to pump filter also?
-Did anyone tried to connect the tank line to teflon braided with clamp? I wondering how flexible/compressible those hoses are. Does it work or should I need a AN to barb fitting and a little piece of clamped rubber hose?

It took me time to figure out what I should do with my lines, but I think I made up my mind. Just got a new fuel pump with 1/4 connection for in, out and return, so I can get rid of almost all rubber hose+clamp connection and have a properly connected return line.

 

[denpo]

No reply on my last post, well, I guess people are getting tired of me asking questions.
However, I think I'm having a good one concerning the fuel return.
Since the section from tank to pump is a low pressure line, I was wondering if it would make sense to have the fuel return line plugged to it, just before the pump connection instead of going all the way back to the tank. The excess of pressure would circle back to the pump inlet, lowering the pressure of the tank to pump line.
What do you think?

 

[big2bird]

No reply on my last post, well, I guess people are getting tired of me asking questions.
However, I think I'm having a good one concerning the fuel return.
Since the section from tank to pump is a low pressure line, I was wondering if it would make sense to have the fuel return line plugged to it, just before the pump connection instead of going all the way back to the tank. The excess of pressure would circle back to the pump inlet, lowering the pressure of the tank to pump line.
What do you think?

I think that if it was a good idea, GM would have jumped at the chance to save the money.
Since the idea of a return line was to reduce vapor lock, I don't think pumping bubbles/warm fuel back in to the supply line is a good idea.
As for fuel filters, they should aways be on the pressure side. Mech pumps do not like to suck thru a filter device. They are internally built like a "trash pump" anyhow.

 

[denpo]

No reply on my last post, well, I guess people are getting tired of me asking questions.
However, I think I'm having a good one concerning the fuel return.
Since the section from tank to pump is a low pressure line, I was wondering if it would make sense to have the fuel return line plugged to it, just before the pump connection instead of going all the way back to the tank. The excess of pressure would circle back to the pump inlet, lowering the pressure of the tank to pump line.
What do you think?

I think that if it was a good idea, GM would have jumped at the chance to save the money.
Since the idea of a return line was to reduce vapor lock, I don't think pumping bubbles/warm fuel back in to the supply line is a good idea.
As for fuel filters, they should aways be on the pressure side. Mech pumps do not like to suck thru a filter device. They are internally built like a "trash pump" anyhow.

Yeah, make sense. The thing is the vapor lock concept is pretty new to me.
I'm taking note on the filter thing.
Thanks for the reply.

 

[mrvette]

No reply on my last post, well, I guess people are getting tired of me asking questions.
However, I think I'm having a good one concerning the fuel return.
Since the section from tank to pump is a low pressure line, I was wondering if it would make sense to have the fuel return line plugged to it, just before the pump connection instead of going all the way back to the tank. The excess of pressure would circle back to the pump inlet, lowering the pressure of the tank to pump line.
What do you think?

I think that if it was a good idea, GM would have jumped at the chance to save the money.
Since the idea of a return line was to reduce vapor lock, I don't think pumping bubbles/warm fuel back in to the supply line is a good idea.
As for fuel filters, they should aways be on the pressure side. Mech pumps do not like to suck thru a filter device. They are internally built like a "trash pump" anyhow.

Yeah, make sense. The thing is the vapor lock concept is pretty new to me.
I'm taking note on the filter thing.
Thanks for the reply.

I have NO idea how a diaphragm stockish mechanical pump would react, but I know a electric FI pump in back with the 1/4" return line spliced back into the pump 3/8" supply line....the pump will make tons of noise, pressure on fuel line is ok, engine runs well, but that pump is under serious stresses by the huge amount of noise it makes.....I don't understand why....just does....

so return for my car now goes to the small add on tank....

:surrender:

 

[010752]

I used 8 AN for supply (1/2") - That's overkill for my engine but it fit the tank outlet pretty good ... pushed it onto the hard line and clamped it down with a SS hose clamp

I used 6 AN for the return, again, it fit the line at the tank

That's strange, I measured my tank line, outlet is 3/8 OD, return and vapor are 1/4 OD. Wouldn't I rather need 6an and 4an an instead of 8an and 6an?

While I'm at it :

-I've seen different filter "size", from 30 microns to 100 microns, which one is adequate for a pump to card filter?
-Is a pump to carb filter enough or should I had a tank to pump filter also?
-Did anyone tried to connect the tank line to teflon braided with clamp? I wondering how flexible/compressible those hoses are. Does it work or should I need a AN to barb fitting and a little piece of clamped rubber hose?

It took me time to figure out what I should do with my lines, but I think I made up my mind. Just got a new fuel pump with 1/4 connection for in, out and return, so I can get rid of almost all rubber hose+clamp connection and have a properly connected return line.

A 100 micron "filter" is the same size as the pickup sock in the tank from the factory and yes it helps to have it. It's also commonly called a suction screen for that reason. Calling it a 100 micron filter just misleads a lot of people.
A 30 micron filter is what carbs normally use.
For FI 10 micron filters are required, but are also an upgrade for carbs.

I personally don't see all the fuss about oem hose and braided line.
Use solid tubing for pressure and good fuel rated hose as the oem did.
The 3/8" line has zero pressure and the 1/4" line 2 psi on a bad day.
Your only concern is whether it becomes hardened and cracks. It will last many years. If worried get a SAEJ1527 rated hose.
If you want pretty, cover it with some chrome spiral wrap.
And the return line will also help keep the fuel pressure more constant. No need not to use it.