Permeation-resistant fuel line hose.

[WKB]

I was chasing what I thought was a slight fuel leak in the boot of the 540. My fuel tank, fuel pump, carbon canister, fuel filter and rubber fuel lines are all in the boot. After double checking all connections, resealing the level sender and pump the smell was still there. To cut a long story short I eventually found that rubber fuel line I was using was the problem. It was letting the unleaded fuel permeate up to 550g/sq mtr/day through the hose. I have approx 2.5 mtrs of 8mm fuel line in my boot. If you work it out that could be as much 34g of petrol permeating into the boot. No wonder there was a smell.
I went to, or rang most of major auto accessory, auto parts or hose suppliers around Brisbane and everyone told they had not heard of this problem.
I rang Speedflow looking for stainless braided telfon fuel line( expensive) to overcome the problem. This salesman was the first person to tell that they knew about the issuses with unleaded petrol permeation. They have two hoses only that can be used with unleaded fuel, stainless braided telfon fuel line and the new 444 series rubber EFI hose.
The 444 series is made to meet the standard SAE 30R9.
I checked my fuel hoses and the breather and vent lines where 30R6, 30R7, or 30R8. The pump and return line was a high performance EFI hose. None of these hoses are recommended for unleaded petrol due to the permeation.
So if anyone is buying any fuel hose for unleaded petrol make sure it has 30R9 on the hose or if you have a fuel smell in your car check to see if you are using the right fuel hose.
Below is a Gates Corporation "Automotive Techtip"

Warren

Avoid comebacks, install permeation-resistant fuel line hose Fuel line hoses carry gasoline from the tank to the fuel pump, to the fuel filter, and to the fuel injection system. While much of the fuel lines are rigid tube,sections of it are made of rubber hose, which absorb engine and road vibrations. There are two basic types of fuel hose: Fuel and oil hoses that meet the SAE 30R7 standard, and fuel injection hose that meets the requirements of SAE 30R9.
Standard fuel and oil (SAE 30R7) hose is rated for low-pressure applications at 50 psi working pressure up to 3/8" size, and 35 psi for sizes over 3/8". This general-purpose hose contains a light reinforcement, and the rubber materials can be any compound that is suitable for fuel, oil and vapors. However, Gates Corporation engineers warn installers that fuel formulations at many US refineries are constantly changing as proprietary blends are introduced according to government mandates and seasonal influences. At times, more aggressive fuels can extract the oils that give SAE 30R7 hose its flexibility. The result is a brittle, stiff tube that will greatly reduce the performance and service life of the hose. Fuel injection (SAE 30R9) hose or MPI (multi-port injection) hose is reinforced to handle higher pressures up to 180 psi. It can be used on all injection systems that use hose clamps. It is not designed to replace coupled assemblies on fuel injection systems.
Fuel injection hose is designed for low permeation contact with a wide variety of alcohols, alcohol fuel blends, and diesel fuel. It allows 15g/m2/day permeation whereas standard SAE 30R7 hose allows 550g/m2/day. (Gates fuel injection hose routinely performs at 1 to 2g/m2/day of fuel loss, well below the allowable standard.) Gates SAE 30R9 hose uses a laminated tube of Fluoroelastomer, as a thin wall inner layer backed by traditional compounds. This first layer protects the rest of the hose from attack, swelling or permeation from aromatics, oxidized gasoline (as can occur in fuel injection systems), ethanol or oxygenate additives and a wide range of petroleum based products.
The laminated tube will resist cracking caused by "sour gas," which forms when unused gas is returned to the fuel tank. As an added benefit, this hose construction reduces emissions because fuel can't evaporate through the hose walls.
SAE30R9 hose is also recommended for diesel fuel because its fluoroelastomer tube resists
deterioration caused by some diesel fuel additives. As refineries produce cleaner fuels and lower allowable permeation rates during the “vehicle at rest” condition, older hose specifications such as SAE 30R7 are becoming less reliable. This type of hose is no longer specified on OEM automotive fuel applications because of stringent permeation
standards.
Therefore, Gates engineers assert that the best choice for automotive fuel line hose applications today is fuel injection SAE30R9 hose. For installers, it is the best choice for reduced comebacks and for high performance, assured trouble free service in a changing fuel environment.
Finally, for submersible applications such as on the in-tank fuel pump, only SAE30R10 hose should be used, because when the hose fails, the pump will fail. Hose construction consists of low swell fluoroelastomer compounds in the tube and cover that resist gasoline and diesel fuel permeation and aging. Standard hoses have these fuel-resistant characteristics in the tube portion only. Contact your Gates jobber for information on Gates MPI/fuel injection hose and submersible fuel line hose.
Gates Corporation