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Discussion Starter · #1 · (Edited)
For the Walbro 255, Bosch 040, etc. fuel pump conversion the correct rating for in-tank fuel hose is SAE 30R10.

NAPA sells hose in the correct diameter for OG 9-3's (and probably others), 5/16" (7.93 mm). Part number NBHH209 for 1 ft. It's not cheap.

Gates Literature:

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 constructed of rigid tube, sections
of it are made of rubber hose, which absorb engine and road vibrations.
There are two basic types of rubber fuel hose used for automotive fuel line replacement:
1. Fuel and oil hoses that meet the SAE 30R7 standard.
2. Fuel injection hose that meet the requirements of SAE 30R9.
Not Recommended: Standard Fuel and Oil (SAE 30R7) Hose
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 engineers warn that this hose is not
suitable for use on any fuel injection system—even as a return line. It is not designed to
handle the pressures or “sour gas” that can form in the return line. In addition, this hose
can emit 30 times more hydro carbons than SAE 30R9 hose, making it a significant
source of pollution.
Recommended: Fuel Injection (SAE 30R9)/MPI Hose
Fuel injection (SAE 30R9) 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, but it should not be used to replace coupled assemblies on fuel injection
Fuel injection hose is designed for low-permeation contact with a wide variety of alcohols
and alcohol fuel blends, such as ethanol, diesel and biodiesel fuel. It allows 15g/m2/day
of fuel loss (well below the allowable standard). Gates SAE 30R9 hose features a thin
inner layer wall constructed with a compound called Fluoroelastomer (FKM), which
resists gas permeation and retards aging. This first layer protects the rest of the hose
from swelling or permeation, which can be caused by aromatics, oxidized gasoline (can
occur in fuel injection systems), ethanol or oxygenate additives, as well as 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 cannot evaporate through the hose walls.
SAE 30R9 hose is also recommended for diesel and biodiesel 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 state that the best choice for automotive fuel line hose
applications today is fuel injection SAE 30R9 hose. For installers, it is the best choice for
reduced comebacks, high performance and assured trouble-free service in a changing
fuel environment.
Finally, for submersible applications such as in-tank fuel pumps, only SAE 30R10 hose
should be used. As gasoline comes in constant contact with the outside of an ordinary
fuel line hose, it can swell and prematurely fail. And when the hose fails, the pump will
Specially engineered to be submersible, Gates Submersible Fuel Line Hose exceeds the
SAE 30R10 rating and is capable of handling gasoline, alcohol-extended gasoline or
diesel fuel in fully immersed, mobile, stationary and marine applications.
Gates Submersible Fuel Line Hose tube and cover contains Fluoroelastomer (FKM), and
is reinforced with aramid fiber—the same fiber used in bulletproof vests that is poundfor-
pound stronger than steel. Click here to learn more about Submersible Fuel Line
For more information contact your Gates representative.

12,348 Posts
NAPA was the only place locally I found that had it in stock. ~$22.00 for a 1 foot length.

1,613 Posts
NAPA will give discounts to account holders. If you work for your local volunteer Fire Dept. or you're the Police or work for a garage that orders from them you may be able to get it for $17,50 or so. Their over the counter sales to non account holders is their highest price. $22 isn't bad because I think it is listed at $31 a foot in their catalog.
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