5/16 nylon or 3/8 rubber fuel line?

[Speedrdr]

MAYBE this is an ignorant question, since copper line wasn’t mentioned, but is there a reason for NOT using copper? Seems like it’s as durable (or better) as nylon is and it for certain is easier to cut/bend/flare than steel. What am I not seeing is the downside? I’m replacing fuel lines front to back. Also doing brake lines from to back, but will be using steel for them.

Randy

 

[Broncobowsher]

So for copper...
It is well known to fatigue and crack from vibrations, that's not good. Back 25 years ago when I was taking my fuels and lubes class back in college there was a discussion about a copper stability test for gasoline. My books are all packed away getting ready for a move and I don't know which box they are in. So a little online research...

"Now, copper interferes significantly in the gum content of gasoline, because it is a catalyst of radicalar oxidation reactions and it accelerates peroxidation. Therefore, this metal must be avoided in any metal alloy that comes into contact with gasoline in the feeding system of engines." https://www.researchgate.net/public...ntent_on_the_Stability_of_Automotive_Gasoline

And it looks like the standard is ASTM D130 Standard Test for Corrosiveness to Copper from a link back to Shell

 

[Yeller]

A different experience Brian, from the aircraft world (yes, I know ) I was helping on an annual inspection a couple of years ago. Oil cooler on back of engine, connected by PTFE hose with stainless braid. One hose had been routed so it had apparently been touching a motor mount tube (4130 chrome moly). I write "had", because the hose had sawed halfway through the tube that it once touched. The only time there could've been relative motion between the hose and the motor mount tube was startup and shutdown, so it had been pretty effective. The stainless braid on the hose looked just fine. Wether it's the saw or the sawed, ya have to be careful how you route and secure the stuff.

Lars I’m with you on this. There is a nice groove in the steering shaft on my Bronco from the pressure line from the pump rubbing on it, 1/32” deep and no broken strands in the hose. Not dissing Brian’s experience, but I find it odd and mark it up to weird stuff happens.

 

[Yeller]

So for copper...
It is well known to fatigue and crack from vibrations, that's not good. Back 25 years ago when I was taking my fuels and lubes class back in college there was a discussion about a copper stability test for gasoline. My books are all packed away getting ready for a move and I don't know which box they are in. So a little online research...

"Now, copper interferes significantly in the gum content of gasoline, because it is a catalyst of radicalar oxidation reactions and it accelerates peroxidation. Therefore, this metal must be avoided in any metal alloy that comes into contact with gasoline in the feeding system of engines." https://www.researchgate.net/public...ntent_on_the_Stability_of_Automotive_Gasoline

And it looks like the standard is ASTM D130 Standard Test for Corrosiveness to Copper from a link back to Shell

I did say copper but not just any copper, Copper Nickel alloy, designed for brakes and hydraulic lines, it is very durable, corrosion resistant and in my experience doesn’t turn green.

As Broncobowsher said never, ever use regular plumbing copper tube, it is well documented for work hardening and failing. Along with the mentioned reactions.

 

[nvrstuk]

Lars I’m with you on this. There is a nice groove in the steering shaft on my Bronco from the pressure line from the pump rubbing on it, 1/32” deep and no broken strands in the hose. Not dissing Brian’s experience, but I find it odd and mark it up to weird stuff happens.

The braided hose actually grooved the strg shaft and no broken strands. Lucky me.

 

[Speedrdr]

Thanks for the info, @Broncobowsher and @Yeller !!! I guess I’ll bending steel lines. Fuel these days is crappy enough without ME having contributed to the problem.

Randy

 

[abn373]

This thread is actually very informative, with information from knowledgeable members. As I posted earlier, now that I am 50 and undoing all the dumbassery I did to my Bronco in the 90s, it really helps. I am considering 5/16" PTFE with a braided covering and AN6 fittings for my carb'd, no return line, system. I actually have had no problems with my current homemade set up, but I know it's not correct. And as payment for the good advice, I just walked out in the garage and took a picture of what I have now, that I did in about 1998, believe it or not so you all could get a good cringe/laugh at it. Hose clamps, rubber hoses, and aluminum tube bent by hand with no flares or fittings well its been trouble free for 25 years, but maybe I need to upgrade to adult status now.

 

[abn373]

This thread is actually very informative, with information from knowledgeable members. As I posted earlier, now that I am 50 and undoing all the dumbassery I did to my Bronco in the 90s, it really helps. I am considering 5/16" PTFE with a braided covering and AN6 fittings for my carb'd, no return line, system. I actually have had no problems with my current homemade set up, but I know it's not correct. And as payment for the good advice, I just walked out in the garage and took a picture of what I have now, that I did in about 1998, believe it or not so you all could get a good cringe/laugh at it. Hose clamps, rubber hoses, and aluminum tube bent by hand with no flares or fittings well its been trouble free for 25 years, but maybe I need to upgrade to adult status now. View attachment 891000

I should have bought stock in hose clamps in the 1990s!!! I would be rich by now

 

[DirtDonk]

Actually that looks pretty sanitary and reasonably well thought out to me. Especially for a 20-something at the time!
So it's not perfectly laid out, you can't argue with success! It worked until you could make it work better. That's a win in my book.
And the rubber looks surprisingly good on the outside still.

Interested to see how it all crossed over though. You said electric pump, right? Is it on the passenger frame rail?

Paul

 

[abn373]

Actually that looks pretty sanitary and reasonably well thought out to me. Especially for a 20-something at the time!
So it's not perfectly laid out, you can't argue with success! It worked until you could make it work better. That's a win in my book.
And the rubber looks surprisingly good on the outside still.

Interested to see how it all crossed over though. You said electric pump, right? Is it on the passenger frame rail?

Paul

Paul, that was my pre-google idea of fixing vapor lock....keep the fuel line away from the heat/motor as long as possible and since the Edelbrock fed in from the passenger side,, and my exhaust is on the driver side... I just decided to route everything on that side so no fuel lines crossed over hot sources. So I bolted a Summit pump to the passenger side frame back by the rear axle and ran it up and over. The funny thing is, I wired a fuel pump shut off to the dash for safety...probably actually a good idea now that I think of it. Oh boy, as I was typing this, I decided to go take a picture because I couldn't remember how I made the fuel lines change sides. Well... I know now apparently all you need to do is a big loop with aluminum tube...Hey, you have to have a little self-deprecating humor .

 

[lars]

I've seen far worse. On airplanes, no less

 

[Yeller]

I've seen far worse. On airplanes, no less

Got a buddy that kept asking me to fly with him...... I pointed out some really baaaaddddddd fuel lines, he has quit asking but is still flying

 

[rockinrich]

I prefer to run stainless hard lines from tank to engine bay. No worries about lines rotting or deteriorating from age. Engine bay lines nylon.


Sent from my iPhone using Tapatalk

so in the engine bay you don't use rubber connections from the pump to the carb/efi connections?

 

[rockinrich]

Nylon is the way to go. Route it inside the frame for protection. If you use good metal (SS, brass, etc.) connections, or fuel-rated plastic connections, you don't need clamps or tools. Just warm the tube, apply a LITTLE clean motor oil to the nipple, & push the tube on. I also use it on my lawn mowers.

good info,thank you!One question,how would you clamp it inside the frame rails?

 

[rockinrich]

Push loc fittings and hoses are pretty good too. I hate steel braided lines.

protects from chaffing or maybe even heat and looks good but still rubber on the inside,thank you.

 

[rockinrich]

Well this is just great thanks for adding to my list of things I should do. Now I am researching PTFE lines because I used metal and rubber lines and hose clamps to redo it all back in the mid-90s and I am currently "updating" wiring and brake lines....AND I guess fuel lines also.

sorry bro! lol

 

[rockinrich]

for my fuel injected 5.0 I use nylon with push lok fittings, may not be needed but I ran the nylon lines inside a rubber hose just to protect it a little bit from road and off road debris And chaffing

some good info,thank you!

 

[rockinrich]

Summit Brand AN fittings and PTFE lined hose are at times half what Earls and others are.

Another option is Parker or your local industrial hydraulic shop. I have bought dozens of AN fittings that were all under $5.

Another option is steel lines but have those steel lines be brake lines. Very inexpensive, easy to form/bend, handle pressures to 1500 psi easily... I have used them in several builds and slid fuel hose over them when sliding them inside the frame rails to protect against any possible noise and vibration. I have actually pulled them out of two of the frame rails both after 10 yrs w/o any noticeable wear. Cheap, easy and a clean frame rail. Just gotta remember they are in there when doing frame mod's.

never even thought about inside the frame rails,thank you!

 

[rockinrich]

Tons of info from all (as always) & one more bit. Braided SS lines are not as abrasion resistant as most think.

I mean a rubber hose probably has more. Protect all hoses from abrasion but don't think that with the outer cover being SS that it is abrasion resistant

My first experience using SS Braided PTFE on my Bronco and I had a vertical hose running parallel to the flat surface of the DS inner fender. Barely touching it, no bends or edges and it wore through in less than a year. My buddy's that were with me could NOT believe it. The hose was flat on that side and worn thru.

I always used construction equip & farm equipment hoses for decades before and they are tough as nails. SS braided underneath the outer coating and tough as nails.

I never knew farm equip hoses had an extra layer of ss braided protection!

 

[gnpenning]

so in the engine bay you don't use rubber connections from the pump to the carb/efi connections?

If the fuel pump is mounted on the motor like a mechanical pump and carb then no. The whole assembly moves together.

The pump to fame mounted fuel lines need to flex since they move separately.

Items that move independently need to be able to flex. Electric fuel pumps the vibration can cause problems.