Replacing Fuel Lines

[BigAl]

The fuel lines on my '93 Nissan Maxima are looking pretty rusty on the underside of the car. Before I give it to my daughter, I think I should replace them. (I did the brake lines already.)

I have done it before using steel brake line material, splicing it into the original lines at the ends, where they aren't too rusty. A mechanic friend just runs rubber fuel hose under the car. I have also seen nylon fuel tubing kits available.

So what's the best approach these days? Anybody want to share their experience?

 

[JakeR22]

I'd rather have rusty original lines, then rubber hose extending from front to back.

See if the fuel lines can be bought new from the dealer.

I have an old '85 S-10. Fuel lines are very rusty and scaly. I would assume if a leak would develope, it'd be a pin hole at first. I would then replace the whole line.

 

[Kestas]

Metal (brake) lines are best. Rubber fuel lines for high pressure systems are very expensive, and not as reliable as metal lines. I imagine it's difficult to snake a metal line through the understructure, but do what you can. You'll probably have to do it in sections with couplers.

 

[BigAl]

That's what I've done in the past. It's not that hard. If I can't re-use the original brackets or clips, I just tie-wrap the new line to the old one every few inches.

 

[ikeepmychevytoo]

Static safety for long section of rubber is a big question here. Pump station ones are expensive earthed special rubber, hence the flowing liquids tend to ccumulate static electic. It is ok for small sections on tight or moving areas like fender to engine but I'd never do an all rubber system.

GM strictly states to use "double wall steel tubing", warning against brass or copper which may develop stress cracks.

Well, anyone know what is a "double wall steel tubing" then? I'm too may need to do this soon. How "double wall steel" can be differentiated from the other ones? Or this simply means seamless pipe?

 

[Kestas]

It's probably the same thing as Bundy tubing. This is what all brake lines are made of. It's basically made of spiral wound steel that is brazed, then extruded... kinda like the inner tube for paper rolls. In cross section it looks like double-walled steel.

 

[Donald]

My guess is that even though it looks rusty on the outside, the wall of the tubing is fine and I would leave it alone. The fuel pressure is very low compared to your brakes or a shop air compressor.

 

[Kestas]

The fuel line in my 91 Mercury developed 3 separate leaks from corrosion in the past two years. I think BigAl is prudent to change the fuel line. I'm guessing his daughter won't be living at home.

 

[JustinH]

be sure to use fuel injection clamps if you are using any rubber in the system.

 

[BigAl]

Quote:

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The fuel line in my 91 Mercury developed 3 separate leaks from corrosion in the past two years. I think BigAl is prudent to change the fuel line. I'm guessing his daughter won't be living at home.

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That's right. My daughter will need the car for an internship at her out-of-state university next semester.

The lines run right along side of the brake lines, which snapped like dry twigs when they were replaced earlier this year. There is a section where there was a shield covering the lines that must have trapped dirt and salt. That section is pretty bad, but the rest of the line looks quite good. . . good enough to accept a flare or coupling.

I'll splice in three 4 foot long pieces side by side to replace that part of the three fuel system lines. I have a double-flaring tool for brake work so I could use the typical brake line couplings, or maybe some steel hydraulic line compression fittings.

I've had fuel line leaks on two old beaters in the past and don't want this one to start leaking hundreds of miles from home in the dead of a snowy South Bend winter.

The gas tank filler tube is also rusted out, but Nissan has agreed to fix that for free under a federally mandated recall I never got notice of a few years back. That's even better than fixing it myself.

 

[Donald]

Some things get expensive. I tried to unscrew the two rubber gas lines going into the fuel sending unit, they go into rubber flex likes for a foot or so. I had a wrench on the coupling on the rubber side and another on the metal side. I thoght it was unscrewing but in reality was twisting the steel fuel line until it snapped as the steel coupling was rusted to the steel line. Thus I needed a $200 fuel sending unit to replace a $50 fuel pump.

It was hard to really see what was happeing as the gas tank was in the way. I would have tried some PB Blaster had I known the picture.

 

[BigAl]

Wow. I think we've all kicked ourselves around the block for doing something like that. Sometimes a botched home repair can get spendy, but I think on the whole, the savings exceed the mistakes.

Last night I went over my fuel lines with a wire brush and scraped around on them with a screwdriver. The lines must have had some kind of plastic coating or heavy varnish on them from the factory. What looked like big chunks of scale was mostly rust-stained flaking coating. I decided that they were more solid than I first thought. After I removed most of the loose stuff, I gooped 'em up good with rubberized black undercoating. I'm pretty confident they'll last until warmer weather next summer, when I'll replace them or get rid of the car.

Solution by procrastination . . . I hope . . .

 

[Kestas]

Up here in the rust belt, undercoating is a must. The expense of undercoating is trivial when compared with what it can save you in the long run, such as fuel line and brake line replacement.

 

[George7941]

I feel that the rubberized undercoatings do not help at all in preventing rust, they trap moisture and causes more rusting than if they had not been used. Ziebart was huge in the eighties, now most rustproofing is with oil and you do not hear of Ziebart any more.

 

[Kestas]

Hence, the reason I keep mentioning Texaco Rust Proof Compound L. It's messy and it drips out in hot weather, but it works. I have 25 years personal experience with it. I just refreshed the undercoatng on my 91 Marquis for the fifth time.