CONTINUOUSWAVE

[This topic began as a sidebar in another thread on another topic. When the sidebar became longer than the original topic, I separated the sidebar into its own thread--jimh]

I suggest [using] the gray marine fuel hose for fuel [supply line to the engine] and vent. [The gray marine fuel hose] is slightly smaller in diameter outside and has a slippery outside coating.

I was able to feed a wire through my fuel [supply line to the engine] and vent line passages to pull new hose through on my 1986 Outrage 18. The wire filled fill hose was the worst part of the process.

The rubber hoses for fuel on boats are rated by the USCG. The hose used to carry fuel to the engine from an internal fuel tank should be rated A1. The A1 rating means the hose is designed to have gasoline fuel in the hose at all times, that is, the lowest permeability, and the hose material has best fire resistance.

Do not use a fuel hose rated B1, as they are not fire resistant. Hoses rated B1 are appropriate for above-deck use, but should not be used to carry fuel under the deck from an internal tank.

Be especially cautious in use of any gray fuel hose with a metallic shiny cover. Those hoses have an awful history of being totally unsuitable for use with gasoline fuel mixed with ethanol. There are many examples of failures of those hoses due to collapse of the inner liner which causes flow restriction. If you plan to use a gray hose, be certain it is from a top supplier and is rated A1.

The federal regulations regarding fuel hoses rating designators are found at

https://www.law.cornell.edu/cfr/text/33/183.540

A prior thread, Modern Gray Fuel Hose: friend or foe? discusses the gray fuel hose problems with delaminating of the inside liner.

The cited earlier discussion

Modern Gray Fuel Hose, friend or foe?

is a good source of information regarding how to recognize poorly made gray fuel hose that has a history of the inner liner debonding from the rubber outer hose covering. Like any product, there are well made instances and poorly made instances. The cited article points out the danger of using gray fuel hose with a shiny metallic gray outer cover.

As I mentioned earlier in this discussion:

jimh wrote:Be especially cautious in use of any gray fuel hose with a metallic shiny cover.

Don SSDD wrote:I would suggest you use the gray marine fuel hose for fuel and vent...

In a recommendation to use "the gray marine fuel hose" there is really no specific product being recommended. As my comment and the excellent article on the topic of gray fuel hoses indicate, considerable caution and judgement needs to be used if the recommendation to use "the gray marine fuel hose" is to be followed, as there are some "gray marine fuel hose[s]" that are not suitable for use with today's modern blended fuels.