TOPIC: Fuel hose failure to be aware of

There are several brands of marine grade fuel hose on the market that can really cause some hair pulling during trouble-shooting if you are not aware of this problem.
Look carefully at the attached picture and you will see how the inside liner of the fuel hose has separated and collapsed - consequently blocking fuel flow.
I find this problem way too often, so I thought I should go ahead and post this for all to consider when confronted by poor performance, odd feeling squeeze bulb behavior, and any issue suggesting fuel delivery problems.
Doc Frankenmerc - Keeping Mercs alive since 1965

Thanks for that Doc. I discovered that just because a fuel line feels soft and pliable doesn't mean it's still good. Mine looked new but when I detached it from the carb a two inch piece just popped right off ! Not a crack in sight just cleanly separated on an invisible line. If that happens after 4 years of storage I can only imagine what some barn finds are like. I've changed all the rubber lines on mine now. Better safe that stranded.

So..what are some good brands to keep an eye out for? Or is it just hit and miss?

I just picked up a '73 Chaparral and a spare fuel hose / bulb is on my list since I've heard of this issue from several people now.

This is why I only purchase non-F-it-all gas for my boat and lawn tools.

Fuel hoses should be changed at least every five years. You should only use USCG hose marked A-15 or B-15, and with the ISO marking 7840.

This meets all USCG and EPA requirements.

The only exception is OEM hose for outboards which. This hose also meets the USCG B-15 but is not marked as such.

What you are seeing here on old hose is the inner liner that was added to fuel hose in the mid 80's to resist alcohol in the fuel. Rather than change the formulation for the hose the manufacturers just added a inner liner that is alcohol resistant, but after years of use these do often separate for the hose walls. Not good. When the outer walls are exposed to alcohol (and some of the other additives in gasoline) the rubber becomes softer and begins to deteriorate. What happens is the parafins in the rubber are leached out of the material. These are what give the hose it's body so without them the hose softens.

There are quite a few hose makers but the most well known are Shields and Trident. They are made in the USA. Be careful of hose made in China. There have been many cases of hose from china that looks just like the real thing complete with markings but they don't meet US or ISO standards.

Don't go cheap on fuel hose. Don't use auto fuel hose, it does not meet the same standards as marine, such as fire resistance. By the way that is the difference between Type A and B. A has to be able to pass a fire resistance test because it is intended for use in locations where there is a potential for fire, like engine rooms. B can be used where there isn't a big risk of fire.

More about fuel hose on my web site (no I am not selling fuel hose) newboatbuilders.com/pages/fuel.html It is about 3/4 down the page.

excellent info! thanks!

I recently had the same problem with a brake flex line on my '63 Corvette. Hard to diagnose a collapsed inner lining, no leak of fluid, no air to bleed out, just no brake!

Since when did a 63 need brakes ? People tend to get out of it's way so they can drool as it passes

I've discovered that the only non-$%#@itol fuel you can buy in Canada is the highest grade they have. Every other blend has 15-25% ethanol added. But it's worth it in the long run. I never thought about the gas for my tractor. It's almost as old as my boats. Hmmmm. Thanks.

I ran into that problem a few years ago with a new fuel supply line that I bought at Gander Mountain. I had to do a little remodeling of the line to get the bulb in the right place for my boat. After that I couldn't get it to pump up or get enough fuel to the carbs to get it to start. After a lot of mumbling, cussing, and a couple beers to clear my head, I took the fittings apart and found the plastic lining had pulled away from the hose and blocked the line,just like the good Doctor explained. I cut a little off the line and carefully pushed in the fitting so I didn't pull the plastic loose again and it has been working fine since.
As usual, thanks Thom for your vast knowledge and your willingness to share with everyone else.
Bill