learn me nylon fuel lines

so im doing the efi fuel system in the duster this coming weekend.

ive been planning on steel 3/8 tube and AN fittings, etc. that stuff adds up QUICK.

working at oreilleys on the weekends, ive discovered that late models are using primarily nylon line. we sell this stuff in 10 foot rolls for cheap. and all the quick connects, etc. its light, and cheap. but I know nothing about it, really.

so, questions: 1. how do you bend it?

1. the fittings seem to be like pex plumbing compression fittings, or barbs. how do these actually work in the long run?

2. is this just a bad idea?

3. where can I find adapters to NPT/AN/steel tube?

my thoughts are to go from the 1/4 npt outputs on the pump to a section of steel line. connect the steel lines to the nylon for the length of the car, up to the fuel rails and regulator (all NPT thread). or, alternately, bring the nylon up to the firewall, and then go to AN to the rails/regulator (for looks). what would I need for this, and would it be better/more durable/cheaper than steel lines and AN fittings?

I may be overthinking this.

Michael

The only time I ever experience nylon fuel lines was with the 320i, and I'm not a fan (they don't move well if one is trying to work or clean around them), though they seem to hold up pretty well.

In all my time on bimmerforums in the e21 section, not sure I heard of a nylon line leaking.

Not sure the method to bend them, or for getting them on the (well, for e21 guys) injector barbs. I think a little heat is used in both cases, with care not to melt the nylon.

Is your Duster running a high pressure fuel system? Wondering why the wish to run nylon...

60psi at the regulator. Efi

Ah, got it.

You might consider viton tubing, supposed to be strong, but it's pricey. It's flexible stuff like fuel hose. I was doing some experimentation before I let my Kjet sit too long and gum up.

All my late 60s to early 70s Opels came with nylon fuel lines, and I have never had a failure I didn't cause. I wouldn't hesitate to use them.

I'd probably run some efi rubber from the tank to a rigidly mounted filter near the tank then nylon to the firewall or wherever 10' gets you and either another filter or something like it rigidly mounted there. Rubber or braided from there.

millions upon millions of cars and trucks are on the road right now with those nylon fuel lines... there is a tool for pushing the ends into the hose- ask around at local repair shops to see if you can borrow theirs if you don't want to spend an extra $100 for the tool.

i don't know how you'd bend it, but in the few GM cars with them that i've torn apart (all 90's Caprices) the line itself didn't have any bends in it, they just sort of picked the straightest shot from the rear of the car to the front of the car and ran it there.

you can get adapters to go from the nylon lines to metric flared fittings and npt pipe fittings. Dorman sells all that stuff, you just gotta dig around on their site- www.dormanproducts.com -for it.

914s had nylon fuel lines in the tunnel. You don't bend it, you put a metal fitting on it with a bend if you need it to go around a corner. McMaster Carr has it, as I recall.

No rubber, no plastic for me and my race cars on EFI and no rubber braided hose either. Use cleaned and caped SS tubing from Mcmaster and AN fittings on the ends where flex is needed use Teflon line braided hose. Use a big GM filter with adapters from Erals to go from AN to the gm bubble fitting.

I had ~2.5 ft of gas rated rubber braided hose and filters in line and still clogged injectors after many mid pack finishes and dyno runs and crap loads of spare parts swapped in to find I'd clogged two set of injectors and more dyno runs the cost of doing it right was cheap.

44Dwarf wrote: No rubber, no plastic for me and my race cars on EFI and no rubber braided hose either. Use cleaned and caped SS tubing from Mcmaster and AN fittings on the ends where flex is needed use Teflon line braided hose. Use a big GM filter with adapters from Erals to go from AN to the gm bubble fitting. I had ~2.5 ft of gas rated rubber braided hose and filters in line and still clogged injectors after many mid pack finishes and dyno runs and crap loads of spare parts swapped in to find I'd clogged two set of injectors and more dyno runs the cost of doing it right was cheap.

^All of this^

I don't go to the extreme of capped stainless but the street cars I've plumbed I've used new steel terminated with swagelok fittings to AN lines at the ends. The race car is all AN lines as the fuel cell is about a foot ahead of the engine. Filtered pickup, filter upstream of the lift pump, high pressure pump has a fine screen, one more porous metallic filter immediately before the fuel rail.

And metal lines only on a race car. I've an aversion to 3rd degree burns...

Ten year ago I was doing a engine swap of a Turbo FI engine into a car that was built when carbs were the way engines came. I tried to use the plastic fuel lines that the OEM used on the turbo engine since the fuel lines were going to see high pressure from the fuel pump near the fuel tank to the engine. I became frustrated in installing the plastic fittings onto the plastic fuel lines. (Ford) I read that you could heat the line in "hot" water and the fitting should just slip in/on to the line. I only had 50% luck doing this and some of the "successful" installs later seeped fuel and I had to install oetiker clamps to seal the connections.

The bottom line is they are fine if their OEM but I won't try to make up me own. I will use high pressure flex line or metal line. My race car is plumbed this way.

http://ls1tech.com/forums/fueling-injection/1085884-nylon-fuel-line-fitting-attachment.html

Are swagelok fittings the ones with the brass barrel? Like you use on gas lines for appliances?

I found them. They are proud of them.

Back to the original plan. Nylon is out, as once I priced everything id need it came up higher.

I'll be running lined braided lines rated for alcohol so the e10 in our area doesn't eat it alive and jam up the system.

Still expensive.

I don't like the idea of nylon in a custom application, OEM I've only seen it between the gas tank and steel line on the chassis, and the steel on the firewall and fuel rail, same for the evap lines, they use steel wherever possible. If you don't find aircraft tolerances or the red/blue color scheme necessary, JIC 37* hydraulic fittings are identical to AN. There should only be a few feet of hose in the system anyways.

Kenny_McCormic wrote: I don't like the idea of nylon in a custom application, OEM I've only seen it between the gas tank and steel line on the chassis, and the steel on the firewall and fuel rail, same for the evap lines, they use steel wherever possible. If you don't find aircraft tolerances or the red/blue color scheme necessary, JIC 37* hydraulic fittings are identical to AN. There should only be a few feet of hose in the system anyways.

the LT1 Caprices (94-96) don't have any steel in the fuel lines except for the fuel filter and the fuel rail on the engine. the rest is nylon lines: one directly from the sending unit to the fuel filter, then one from the filter to the fuel rail, then the return line from the regulator to the sending unit. i think the later (98-02, but also maybe the 93-97)F bodies are the same way.

Dusterbd13 wrote: Are swagelok fittings the ones with the brass barrel? Like you use on gas lines for appliances?

No swagelock are a double ferell type fitting normaly 304 or 316 SS and yes price is high but so is a night in a burn ward. There good for pressure and vacuum and are cleaned and capped for 5 nines (99.99999pure) gas usage.

Everyone stop saying "Swagelok" now. That's like saying Kleenex. Well, it would be if Kleenex cost 2-3x what its competitors do.

Parker, Ham-let, Hy-lok, and a lot of other quality companies make excellent compression tube fittings.

That said, I wouldn't use them in a fuel system. They are weird to tighten (they tighten based on # of turns instead of torque), and they can only be tightened a few times. There are better ways, some of them are face-seal fittings.

This is a fuel system though, and I don't have much experience there, I can only speak from another industry.