Rubber fuel lines

[n33k0]

I've read dozens of articles and even more forum posts regarding the use of rubber fuel lines. A lot of people say its a bad idea, but there are just as many people who say "I've never had any trouble with them". When I bought my truck it had a rubber line connecting the fuel pump to the carb, and I thought that if I inspected it often I could catch any leaks before it became a serious problem. I had driven the truck like that for close to 1.5 years, checking the fuel line for cracks or leaks often, without any issues.

Yesterday I drove my truck to work and noticed a stronger-than-usual smell of gas. I didn't think much of it at first, maybe I had pumped the accelerator too many times before starting the engine (no choke). I drove the 4 or 5 miles to work, which takes about 20 minutes in morning traffic (plenty of time for the engine to get nice and hot), and parked the truck. Lunch time comes around and I decide to pass by home to check the mail, and I notice the smell of gas again... now I'm starting to worry because I didn't pump the accelerator before starting the engine this time. I decide to keep driving home, which in hindsight was a stupid idea, but I thought "it's only a couple more miles."

When I get home I shut the truck off and open the hood and notice a small fuel leak where the rubber fuel line meets the carb fuel inlet. Keeping the hood open, I decide to turn the engine over and watch the carb to see what happens, I can see into the engine bay through the gap between the open hood and cowl. When I turn the key I see fuel spraying everywhere, soaking the entire passenger side of the engine bay; battery, alternator, A/C and heater hoses, and probably the header too. My jaw dropped, I couldn't believe that I was able to drive anywhere with all that fuel spraying around the engine. I noticed a large pool of gas on the lip of the front crossmember, too. There was an angel up there working overtime making sure I didn't go up in flames that morning.

Needless to say, I haven't driven the truck since then, not until I get a new fuel line installed. I always made an effort to inspect the rubber line often, and the last time I had looked at it was five days ago (also the last time I drove the truck). I suppose the fuel line did work as described on the packaging, there wasn't any deterioration of the rubber due to the gas running through it; but the rubber did fall apart where it connected to the various fittings (fuel pump, fuel filter, carb inlet). It seems like the clamp used to keep the line connected cut into the rubber and over time it wore all the way through. I used a clamp with rolled edges, "designed to prevent sharp metal edges that would cut into rubber lines" according to the manufacturer, but that didn't work out as intended. I'm sure the heat cycles in the engine bay didn't help the rubber, either.

In summary, for those who don't like reading: Rubber fuel line broke, didn't notice and drove the truck, gas everywhere, no fire (extremely lucky), going to plumb a new fuel line that is not rubber.

[thedudeabides86]

Originally Posted by n33k0

I've read dozens of articles and even more forum posts regarding the use of rubber fuel lines. A lot of people say its a bad idea, but there are just as many people who say "I've never had any trouble with them". When I bought my truck it had a rubber line connecting the fuel pump to the carb, and I thought that if I inspected it often I could catch any leaks before it became a serious problem. I had driven the truck like that for close to 1.5 years, checking the fuel line for cracks or leaks often, without any issues.

Yesterday I drove my truck to work and noticed a stronger-than-usual smell of gas. I didn't think much of it at first, maybe I had pumped the accelerator too many times before starting the engine (no choke). I drove the 4 or 5 miles to work, which takes about 20 minutes in morning traffic (plenty of time for the engine to get nice and hot), and parked the truck. Lunch time comes around and I decide to pass by home to check the mail, and I notice the smell of gas again... now I'm starting to worry because I didn't pump the accelerator before starting the engine this time. I decide to keep driving home, which in hindsight was a stupid idea, but I thought "it's only a couple more miles."

When I get home I shut the truck off and open the hood and notice a small fuel leak where the rubber fuel line meets the carb fuel inlet. Keeping the hood open, I decide to turn the engine over and watch the carb to see what happens, I can see into the engine bay through the gap between the open hood and cowl. When I turn the key I see fuel spraying everywhere, soaking the entire passenger side of the engine bay; battery, alternator, A/C and heater hoses, and probably the header too. My jaw dropped, I couldn't believe that I was able to drive anywhere with all that fuel spraying around the engine. I noticed a large pool of gas on the lip of the front crossmember, too. There was an angel up there working overtime making sure I didn't go up in flames that morning.

Needless to say, I haven't driven the truck since then, not until I get a new fuel line installed. I always made an effort to inspect the rubber line often, and the last time I had looked at it was five days ago (also the last time I drove the truck). I suppose the fuel line did work as described on the packaging, there wasn't any deterioration of the rubber due to the gas running through it; but the rubber did fall apart where it connected to the various fittings (fuel pump, fuel filter, carb inlet). It seems like the clamp used to keep the line connected cut into the rubber and over time it wore all the way through. I used a clamp with rolled edges, "designed to prevent sharp metal edges that would cut into rubber lines" according to the manufacturer, but that didn't work out as intended. I'm sure the heat cycles in the engine bay didn't help the rubber, either.

In summary, for those who don't like reading: Rubber fuel line broke, didn't notice and drove the truck, gas everywhere, no fire (extremely lucky), going to plumb a new fuel line that is not rubber.

Wow, glad nothing ugly went wrong with your truck. I've got rubber fuel lines and just dropped a new motor in and need to redo some line, so I'll be using steel lines just in case. Thanks for sharing your mishap.

[cypressbog]

Guys! Never, ever use rubber fuel line around your engine, period.

[drfloyd]

Rubber fuel lines? Who could have possibly recommended rubber for fuel lines? That thought would never even cross my mind.

[Gmc.guy]

Remember that steel lines with poor flares and kinked bends can fail just as easy or easier. A steel line that is tightened down under tension or rub thin can also fail

[drfloyd]

That's true but as long as there are no leaks initially and no places for suspect abrasion, steel lines are perfectly safe. Not so with rubber. That's a time bomb.

[tommys72]

So what are you guys doing for a fuel line and a fuel filter with a stock pump and an edelbrock carb? I want stock looking as possible, nothing that looks like a race truck

[thedudeabides86]

Originally Posted by cypressbog

Guys! Never, ever use rubber fuel line around your engine, period.

Is there a good place to find pre-bent lines? Otherwise I'd just rent a pipe bender from O-Reilly and bend the lines myself.

[n33k0]

Originally Posted by drfloyd

Rubber fuel lines? Who could have possibly recommended rubber for fuel lines? That thought would never even cross my mind.

It was one of those moments that seemed OK at the time, but is obviously very dangerous in hindsight. It was easy to shrug off the warnings, I thought "those guys on the internet are just worry-warts... I'll inspect the line before every drive and be fine." Well sometimes you're in a rush and forget to look under the hood before driving off down the road.

Then comes the laziness. You got a new carb and now your old fuel line doesn't reach the new inlet, so you run to the parts store and get some rubber lines "just for now, to make sure it runs". You drive the truck a few times and it seems to hold up well, and then that temporary fix becomes permanent.

This was a lesson I learned the hard way, I'm just thankful I got off with "just a warning".

[jjlett69]

Im going to be the devils advocate here on rubber fuel lines...
I am re-assymbling my truck and currently re-plumbing all lines including my fuel line with 3/8 aluminum tubing. I totally agree with everyone on rubber fuel lines, that you are playing with fire and trust me i have had my share of leaks lol. However it is not usually the rubber line itself that fails, more like the connection points. Not using proper clamps or overtightning the clamps, to aggressive of bends to hard lines, hardlines that arent bubbled flared, etc. Lets face it, all steel braided hoses are rubber line essentially, however the strength and durability really lies in quality of the AN fittings installed and done right. Also i totally agree with the above post on most of us just throw some rubber line in there with a 99 cent hose clamp, get it running and forget about it. just my two cents! Keep up these awesome threads, i have learned so much from them!

[Jack_71C10]

Just a question: What are you anti-rubber guys using for areas where the fuel line needs to flex. If you run steel lines from your frame to the fuel pump (or engine for electric fuel pumps) the steel with fatigue and break from being bent back and forth. From the factory several locations used rubber for this reason. New cars switched over to nylon several years ago, but these require special fittings. Braided hoses could be a choice but they are still rubber and the rubber is what keeps the fuel in, so this would fail just as quick as a rubber hose. I would like to redo my fuel lines but I never hear any suggestions for a replacement in these areas.

[dmjlambert]

I would think cab to frame and frame to fuel pump are OK for hose, as those are as-designed, and are not under pressure, and not likely to spray if they get compromised. I bought the 2-foot section of fuel hose LMC sells and it is thin and flexible compared to the fuel-injection-approved hose I got from O'Reilly. The fuel-injection hose was not flexible enough to make the s-bend from frame to fuel pump without kinking. The LMC hose came with little green springy clamps that you pinch open with pliers and when you let them go they clamp gently. I'm thinking that may be the ideal clamp for the sections of fuel line that are not under pressure from a fuel pump.

[garyd1961]

"noticed a stronger-than-usual smell of gas."
You smelled gas but yet you continued to drive the truck? Any gas smell should be checked out at once not when it gets stronger-than-usual.
I have a combination of metal and rubber lines. I know leaks can happen so I do check under my hood often and I will not drive any vehicle if I smell gas.

[Overdriven]

When you look at what vehicles come with from the factory, its hardline, or at least mostly hardline with just a little bit of rubber. Most racing sanctioning bodies also want less than 12" of rubber hose if any at all depending on the class. These facts were never lost on me and I bought my tubing bender and flaring tools long ago.

A buddy of mine felt the same about rubber and thought braided would be better. He did everything right, from the fittings to routing and mounting. And all was well for about 5 years until he started smelling gas from the rubber deteriorating. Fumes then gas seeping out the lines and it wasn't some cheap no name brand either. After that he went hardline and used some braided for a flex point going to the carb from the chassis. That braided line recently started leaking.

Manufacturers have come up with a solution to the problem though. I think it's called PTFE and you can get it in plain rubber and braided. It's the only stuff I'll use when I need a flex point. Btw Napa carries AC Delco's version of this line and it's ethanol safe. So if you really need a short piece of rubber hose it's not hard to find something better than generic no name hose.

[70STOVEBOLT]

Originally Posted by tommys72

So what are you guys doing for a fuel line and a fuel filter with a stock pump and an edelbrock carb? I want stock looking as possible, nothing that looks like a race truck

I bought Edelbrock's fuel line kit with inline filter. I also plumbed in a regulator and gauge. I made a line at work with the PTFE inner tube and braided stainless steel outer cover and crimped ends. It is hard to see the fuel line, it runs under the electric choke. I will post a pic.

[70STOVEBOLT]

Here is a pic

[Gmc.guy]

What drives me nuts is a regulator and line fastened to inner fender. Tank to frame to inner fender. Then a line hanging across for 2 feet to carb. No cutoff switch from oil pressure switch or something. That's way more dangerous if you were to get in an accident I see that lots on HP builds

[dmjlambert]

Well, the hot rod builds are one thing and that does sound like trouble, but I'm still worried about plain stock builds now that I'm reading more and more online, even for the non-pressured lines. It would not be possible to use PTFE with the stock frame-mounted hard line and the stock mechanical fuel pump, is that right? PTFE does not work with clamps, as best I can figure by reading online, and the hard line on the frame and the fuel pump does not take a fitting, you must have a hose with clamp. I would like to use something more modern-fuel-resistant than Gates 30R7 hose.

I am contemplating this stuff, what do you guys think?
https://www.belmetric.com/multifuel-...mm-p-3722.html

[mooseboy84]

If you got money for an fittings and hoses, then go ahead, otherwise rubber lines are fine, cheap and easy to replace. Rubber gets hard and can crack especially if car sits very long periods without any use, but its easy to inspect and realitively cheap to replace. You can get 25' of summit brand rubber hose for $20 which is good quality and fine to use. You can bend rubber and if it's to hard it should be replaced. Anything can and will fail eventually, even if recently inspected.

[special-K]

I would have looked under the hood at work after smelling the fuel, knowing the risks that come with rubber fuel line. Often the issue is wrong type of hose. There is hose made specifically for this use. All these trucks have a short piece from tank to fuel line and it lasts fr years. Some still have the original piece. Under the hood exposed to heat shortens the life and increases the risk. Awareness and inspection, especially when you smell fuel, is the key. You can keep a spare length in the glovebox and replace in 5 minutes.
A steel line can be rubbing through against the frame, at the hold-down, or even the fitting and you don't know till it smells or drips. They can also rust out on the frame. The original line seems to stand up to corrosion just fine. But, who hasn't herd of the '88-up truck lines rotting away? It's a problem on every GMT400 and newer. Same with brake lines. The key is be aware, look, smell, observe the condition of your fuel lines. Heck, a carburetor can leak fuel. And use rubber line to a minimum if used at all. That's what GM did when they built your truck

[Overdriven]

Originally Posted by dmjlambert

Well, the hot rod builds are one thing and that does sound like trouble, but I'm still worried about plain stock builds now that I'm reading more and more online, even for the non-pressured lines. It would not be possible to use PTFE with the stock frame-mounted hard line and the stock mechanical fuel pump, is that right? PTFE does not work with clamps, as best I can figure by reading online, and the hard line on the frame and the fuel pump does not take a fitting, you must have a hose with clamp. I would like to use something more modern-fuel-resistant than Gates 30R7 hose.

I am contemplating this stuff, what do you guys think?
https://www.belmetric.com/multifuel-...mm-p-3722.html

The frame mounted hardline can be flared so you can use an adapter to AN fittings which are required for PTFE line. But if you can't change the fitting on your fuel pump and are stuck with a regular old hose barb then you're stuck with regular old hose and hose clamps. In those cases I now use AC Delco Barricade/Green Shield hose which has an inner liner meant for all fuels. Saw it on Hot Rod Garage during 1st season, it's homeless Dave approved and so far been good for me. http://www.napabeltshose.com/~/media...20Brochure.pdf

[scooterpimp]

Fuel injection hose works well in flex areas , using zero gap style clamps .

[dmjlambert]

Fuel injection hose does not work well between stock frame line and stock mechanical pump on my 350 for the reason described in my earlier post, does not flex without kinking. And the typical fuel injection hose available at part stores such as O'Reilly is not suitable for modern gas, it appears. This Barricade Carburetion Hose that Overdriven gave the PDF brochure for seems ideal, and it works with clamps. I am going to give it a try.

[n33k0]

Originally Posted by garyd1961

"noticed a stronger-than-usual smell of gas."
You smelled gas but yet you continued to drive the truck? Any gas smell should be checked out at once not when it gets stronger-than-usual.
I have a combination of metal and rubber lines. I know leaks can happen so I do check under my hood often and I will not drive any vehicle if I smell gas.

Yeah, in hindsight it was a stupid decision. Smelling fuel is not uncommon with my truck, whether its an out of tune carb running rich or too many pumps of the accelerator on a cold start... coupled with being in a rush, late for work that morning, it was a very bad decision that could have ended much worse than it did for me.

Originally Posted by special-K

I would have looked under the hood at work after smelling the fuel, knowing the risks that come with rubber fuel line. Often the issue is wrong type of hose. There is hose made specifically for this use. All these trucks have a short piece from tank to fuel line and it lasts fr years. Some still have the original piece. Under the hood exposed to heat shortens the life and increases the risk. Awareness and inspection, especially when you smell fuel, is the key. You can keep a spare length in the glovebox and replace in 5 minutes.
A steel line can be rubbing through against the frame, at the hold-down, or even the fitting and you don't know till it smells or drips. They can also rust out on the frame. The original line seems to stand up to corrosion just fine. But, who hasn't herd of the '88-up truck lines rotting away? It's a problem on every GMT400 and newer. Same with brake lines. The key is be aware, look, smell, observe the condition of your fuel lines. Heck, a carburetor can leak fuel. And use rubber line to a minimum if used at all. That's what GM did when they built your truck

I think the heat and clamps are what eventually cause the rubber line to fail. At a glance the rubber looked perfectly normal, but close inspection of the ends that were clamped to the pump, filter, and carb showed that the clamps were wearing through the rubber. Despite the clamps having "soft" edges and not being over tightened, they still tore up the rubber line.

I'm currently bending a hard line to connect the pump to the carb, but I still haven't figured out the best way to route the line. I'm also unsure how to connect the fuel filter; cut a portion of the steel line and replace it with the filter and two short rubber hose lengths with clamps?

[tommys72]

Thanks 70stovebolt!