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Nylon Tubing and Barbed Fittings

12/17/2009 8:21 AM

Hi everyone. I am trying to install semi rigid high-strength 5\16" nylon tubing on Ford duckbill fuel line connectors. They are the fittings with the barbed ends. I have tried heating the tubing in boiling water with very little success. I have also heated the nylon tube above open flame with better results but with some damage to the tube. I understand I can substitute other types of "flexible" tubing for fuel line as long as the max pressure rating exceeds 80-100psi but would like to use nylon if possible. Is anyone familiar with the method used to assemble the connectors during the manufacturing process or is there some sort of tool I cant seem to find on the net for this? I already know the line size ID will\has worked with the fitting as I took it off a donor car. Thank you.

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Guru
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#1

Re: Nylon Tubing and Barbed Fittings

12/17/2009 8:57 AM

It is recommended to use a compression fitting when using nylon tubing as a fuel line. Nylon does not grip a barb fitting well. It's not pliable enough to contact around the barbs. If you wish to use nylon tubing replace the barb fitting with compression fittings. If the barb fitting is to be used recommend Tygon or other pvc tubing rate for fuel.

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#2
In reply to #1

Re: Nylon Tubing and Barbed Fittings

12/17/2009 9:13 AM

Thank you for the reply. One question. The car comes from the factory with the spring-loc fittings (barbed) stainless steel to nylon on the fuel rail

and plastic barbed (duckbill or d-lock) to nylon hose on the fuel filter. How is it recommended to use compression fittings when it comes from Detriot like this? Thanks.

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#5
In reply to #2

Re: Nylon Tubing and Barbed Fittings

12/17/2009 11:31 AM

Are you sure it's nylon?

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#6
In reply to #5

Re: Nylon Tubing and Barbed Fittings

12/17/2009 11:47 AM

I am fairly certain it is nylon. And can be purchased in bulk or can buy a repair kit to be spliced with barbed style fittings:

EFI Nylon Fuel Line Tubing

"This is same tubing that Ford uses on their fuel injected production vehicles
To be used with Stock Ford Fuel Fittings
Safer than steel tubing
Sold by the Foot"

AND

Dorman 800057 Nylon Fuel Line Repairkit

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#8
In reply to #6

Re: Nylon Tubing and Barbed Fittings

12/17/2009 2:32 PM

Did you try a heatgun or hair dryer may work to get the tubing pliable enough to push over the barbed fitting?

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#3

Re: Nylon Tubing and Barbed Fittings

12/17/2009 9:46 AM

Boiling water usually works, but don't dip too much of the end into it else you no longer have a stiff tube to push, it also takes a minute in the water to soften it. Sometimes cutting the end of the tube at an angle will help get it started.
I do however agree with those who say that nylon isn't ideal for push on as it doesn't have much memory.
It's used a lot for pumping rinse aid in comercial dishwashers etc, and rinseaid is good at finding gaps, also it's pumped at 2-3 bar quite often.
Del

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#4
In reply to #3

Re: Nylon Tubing and Barbed Fittings

12/17/2009 10:17 AM

Ok I agree with Del (as always) but I would still like to know how these are manufactured\assembled....heat gun perhaps? And at what temperature.

I plan on simply cutting off the nylon line and using a 5\16" line with stainless steel ear clamps for that factory look. The hose I have in mind is Polyethelene Tubing with temp rang -50-140deg and psi rated at 125. But there are many options...High Density Polyethelene, Polyurethane, Flexible Polyethelene, etc... I suppose I could be over doing it and should just go to the local auto patrs store and ask for standard EFI fulel line and be done. Any suggestions as to the fuel line type?

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#7

Re: Nylon Tubing and Barbed Fittings

12/17/2009 12:54 PM

If you are pushing onto metal fittings...get the metal fitting warm too.
Del

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#9

Re: Nylon Tubing and Barbed Fittings

12/18/2009 8:20 AM

You should check out how PEX tubing is installed. It uses an expanding collet to to open the tube end and when removed, must be installed onto the fitting very quickly.

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#10
In reply to #9

Re: Nylon Tubing and Barbed Fittings

12/18/2009 8:28 AM

I will investigate PEX. I boiled the tubing for about 5min. with no luck. I have ordered some samples and will try installing new virgin tube. There are many options as far as ID and wall thickness plus metric sizes also available. I will mic my fittings and see which one of the samples best fits my application. I have a feeling the stuff I am working with has reached its useful life...1993 Mercury (16yrs.)

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#11

Re: Nylon Tubing and Barbed Fittings

12/18/2009 8:41 AM

I work with fuel lines all the time. The best way I found to push the hose over the barb is use a little mineral spirits and a plumbing flaring tool. Lay the end of the hose in a small cup of mineral spirits for five minutes. Then grip the hose directly beneath the area where the barb will end up and tighten the flaring tool like it were a piece of copper tubing. Next use the other part of the flaring tube tool (the spinning flaring end) to push the barb into the tube like you would be flaring the end of the copper tube. Works like a pulley puller but in reverse. It pushes the barb right into place and it won't leak or come off. Good Luck.

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#13
In reply to #11

Re: Nylon Tubing and Barbed Fittings

12/18/2009 12:23 PM

I'll give you a GA for that.

Picture in post 6 shows an assembled fitting. It appears this is the way most of the kits are sold... there must be some special assembly jig used to accomplish this. Your solution sound reasonable, do-able, and he probably has a flare tool already. jturley, please let us know of success / failure of this idea, would you?

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#14
In reply to #13

Re: Nylon Tubing and Barbed Fittings

12/18/2009 12:27 PM

Yes I will try this tonight and post results. I do have the flare tool in the garage but never thought of using it that way. Thanks for the ideas. Jim

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#15
In reply to #11

Re: Nylon Tubing and Barbed Fittings

12/18/2009 12:52 PM

I'm afraid the tool might cut into the tubing when tightened around it. Those little serrations on the inside of the jaws will bite right into the tubing and give you a perfect failure point.

Just a thought, never done it myself.

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#16
In reply to #15

Re: Nylon Tubing and Barbed Fittings

12/18/2009 12:59 PM

I thought I might use a piece of tape to protect the tubing.

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#12

Re: Nylon Tubing and Barbed Fittings

12/18/2009 8:54 AM

Use a heat gun to warm up your tubing, carefully though.

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#17

Re: Nylon Tubing and Barbed Fittings

12/18/2009 9:36 PM

Nylon has a melt temp of 490-520 deg F. Boiling water at 212 is still a little cold. A heat gun should help. The factory probably has heat lamps and a special fixture to push these togeather. Good luck.

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#18
In reply to #17

Re: Nylon Tubing and Barbed Fittings

12/21/2009 8:13 AM

I am going to borrow a heat gun today and give it a try. I tried using a brake flare tool to hold the nylon tube and to get a little leverage but it had the same effect...none! The 212 water does soften the nylon but not enough. Thanks.

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#19

Re: Nylon Tubing and Barbed Fittings

12/21/2009 8:53 AM
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#20

Re: Nylon Tubing and Barbed Fittings

12/21/2009 5:49 PM

The problem with nylon is that it is a semi-crystaline material. This means that most nylons will change from a stiff solid to a liquid within a very short temperature range. In a production environment, the tubing (if it is nylon) is probably heated to a precise temperature before being pressed over the barbed fitting. As another poster mentioned, boiling water is not hot enough to accomplish this job. Using a heat gun may not bring it to the precise temperature to allow the tubing to stretch without melting.

Just a thought, you may have to heat the tubing and the barbed fitting both to be able to assemble them. A cold fitting may pull the heat out of the tubing too quickly to assemble the tubing.

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#21

Re: Nylon Tubing and Barbed Fittings

12/25/2009 8:56 PM

For many years, that type of fuel line was used on Jaguar E Types and is readily available from restoration supply houses such as this. They can also instruct you on the technique to install it properly. I would caution that when this hose was used, pump pressures were typically 5-8 psi or so. If you are using this for a fuel injected system, it may be seeing 40 psi or more. Personally, I would contact the dealer and have a mechanic tell you what is involved in installing it. Or just use quality hose clamps and be done with it. I realize it is a specially designed connector. It probably requires a specially designed replacement part. We don't want any carbeques.

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Del the cat (2); Doorman (1); Jaguar (1); jturley (7); lyn (1); MIKE L. (1); MrM (1); ozzb (3); pantaz (1); shriketexas (1); vapsterinventor (1); Zoomer (1)

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