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Nylon fuel lines

General engine tech -- Drag Racing to Circle Track

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travis
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Nylon fuel lines

Post by travis »

Today I finally got my repaired fuel tank sender back for the rear tank on my ‘87 F150. This was a fiasco in itself because apparently ‘87 is an oddball year with it being the first year of this body style, and the last year with a carb. Anyway...of course when I went to connect the fuel line to the sender, the end of the plastic or nylon connector disintegrated in my hand. Once I cleaned the dirt and crud off the line to see what I was working with, that was when I found that the entire fuel line setup is all nylon #-o This is a dual tank system with a switch over valve located about midship, with everything running on the drivers side of the frame. Now from the factory, these things have the exhaust system running down the passenger side. But I have headers and duals running down both sides...

From what I’ve read, it seems these nylon lines are highly effected by even low levels of heat. Should I be concerned about having 1 exhaust pipe anywhere in the vicinity of this nylon line? I’ve never experienced this stuff before.
travis
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Re: Nylon fuel lines

Post by travis »

I’m guessing by the crickets nobody else has messed with this stuff either?
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Re: Nylon fuel lines

Post by Kevin Johnson »

travis wrote: Wed Nov 18, 2020 8:22 am I’m guessing by the crickets nobody else has messed with this stuff either?
I checked some threads and one good suggestion was to use some heat reflective wrapping on the fuel line anywhere it comes near a heat source.

The old California Forestry study gave temperature values at various points in full length exhausts. Curves/bends get heated up significantly more despite being a good distance away from the motor (hi Randy).
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Re: Nylon fuel lines

Post by rebelrouser »

I have one of these fuel line repairs kits for repairing issues like you mentioned

https://www.oreillyauto.com/detail/b/do ... 7457?pos=1

I don't think the heat is such a big issue as the alcohol in the fuel, in 1987 we were not putting alcohol in our fuel, so engineers did not select materials to be compatible with alcohol. The local gas station at my home has alcohol free premium, all my yard equipment, outboard motors, and my collector cars, all run on that, and I have very little issues. I however still see carbs full of nasty stuff, fuel lines hard and brittle, etc. from others, who do not follow my advice on fuels. I have a buddy who has an extensive car collection, he has been using 110 race fuel in the tank when he stores his vehicles, and it seems to work very well to stop fuel system damage.
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Re: Nylon fuel lines

Post by dannobee »

GM has used the plastic lines since the late 80's. The failure rate is far lower than the metal lines with rubber hose between the sections (the rubber deteriorates far faster than plastic).

I don't know what Ford used, but the GM stuff was tough as hell. And not affected by alcohol in the fuel.
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Re: Nylon fuel lines

Post by Moparboy440 »

Normal PA11 nylon tubing works great with Gasoline and Ethanol at temperatures up to 60*C. When you go over 70*C they start to detoriate quite fast.
If you want a really good quality temperature resistant tube go to your local Parker store and ask for their Legris Teflon tube.
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Re: Nylon fuel lines

Post by travis »

I farted with this thing some today after finding some replacement connections locally. It seems that even with a heat gun, you can’t really install the barbed fittings into the line by hand...at least not while the line in still in the vehicle. So it looks like I need to get the proper tool to install fittings if this is the route I’m going to take.

What is y’all’s opinion of nylon fuel lines in a performance application? I did some research, and the manufacturers FWIW say that this stuff is impervious to alcohol laced fuels and even recommend it up to around 200psi line pressure. I won’t be running anything crazy like that...this will be a mechanical fuel pump and carb application. It seems like it would be much easier to route around all the crap I have to work around on the rear half of this truck.

This truck is getting a fairly strong 450-500hp 351w based stroker in the near future. I can run a steel line from just forward of the rear axle to the engine bay, if exhaust heat is a concern. The plan is to remove the saddle tank and do away with the switch over valve. The lines are 3/8” from both tanks to the switch over valve, then 5/16” from the valve to the engine, which would have to be upsized for sure.
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Re: Nylon fuel lines

Post by swampbuggy »

The best Copper line ( easier to work with ) might be an option to consider where you mentioned running the steel line ?? Mark H.
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Re: Nylon fuel lines

Post by englertracing »

https://www.mcmaster.com/fuel-tubing/ex ... chemicals/

I've used this before to replace the hard plastic tubing to and from the fuel rail
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Re: Nylon fuel lines

Post by Sparksalot »

swampbuggy wrote: Wed Nov 18, 2020 8:21 pm The best Copper line ( easier to work with ) might be an option to consider where you mentioned running the steel line ?? Mark H.
Copper tubing is dangerous in applications subject to vibration such as on a vehicle, especially in a use carrying fuel. It can work harden and crack. Not good!
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Re: Nylon fuel lines

Post by Sparksalot »

englertracing wrote: Wed Nov 18, 2020 10:41 pm https://www.mcmaster.com/fuel-tubing/ex ... chemicals/

I've used this before to replace the hard plastic tubing to and from the fuel rail
A strong second recommendation for this tubing, it's good for the application.
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Re: Nylon fuel lines

Post by MadBill »

Sparksalot wrote: Thu Nov 19, 2020 2:20 am
swampbuggy wrote: Wed Nov 18, 2020 8:21 pm The best Copper line ( easier to work with ) might be an option to consider where you mentioned running the steel line ?? Mark H.
Copper tubing is dangerous in applications subject to vibration such as on a vehicle, especially in a use carrying fuel. It can work harden and crack. Not good!
2X for work hardening/fatigue cracking with copper! Decades ago my pal built a tunnel-rammed 350 SBC ski boat and made beautifully shaped and polished copper fuel lines. After less than 10 hours running, one line cracked and started filling the bilge with Sunoco 260... :shock:
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Re: Nylon fuel lines

Post by Bill Chase »

swampbuggy wrote: Wed Nov 18, 2020 8:21 pm The best Copper line ( easier to work with ) might be an option to consider where you mentioned running the steel line ?? Mark H.
3/8 nicopp line is a little salty, but if you buy it as a premade brake line from advance auto a 6 foot stick of it is like 12 bucks. it bends easy, super easy to put a flare on. i have recently worked with this stuff and it really is great. much easier to work with than steel line. the fact that it is mostly copper alloy it seems like even if ran in close proximity to heat it would dissipate it quicker. maybe coil up a few coils as the line comes off the frame rail before feeding into the mechanical pump. sort of a poor mans cool can. as long as it was getting lots of airflow from the rad fan it couldnt hurt.
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Re: Nylon fuel lines

Post by autogear »

Ive used a lot of NiCopp. It doesnt work harden or split. But inspectors hate it sometimes LOL

Or use the replacement plastic linked above
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Re: Nylon fuel lines

Post by travis »

I’ve never used Nicopp, but it’s sounds very interesting....especially if it’s easier to work with than steel. Would you consider it durable enough for long term (as in years and years) use as a fuel line?
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