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Still needs a life.
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Discussion Starter #1
There has been a recent epidemic of disintegrating fuel hoses reported in the ST clubhouse. Has anyone noticed a pattern as far as time or mileage that could be incorporated into the routine maintenance schedule?
 

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Mr Leakered
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Could it possilby be the recent change to add 5% more ethanol to the fuel (10% total)? It might be enough to kill off what life might be left in the lines.

There does seem to be a rash of these issues. But then, the STs are an aging fleet.

I'm ordering up some fuel hose to go with the valve check that I have coming up. I'm also thinking about modifying the system to have the filter external to the tank. This would allow me to open up the tank once every 4yrs or so to replace the fuel lines.

Have a good one.
 

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I wonder if the increase in fuel line problems has anything to do with our poor quality fuel that we now have to live with? We pay a premium price for gasoline now but receive a high percentage of non petroleum product in are gas. I suspect alcohol as being the problem. Rubber doesn't like alcohol.

Jerry
04 ST4s
 

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The days are getting longer!
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+1 Just a theory. I know a lot of people with outboard motors that are having fuel line problems also.
 

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Not sure the fuel has anything to do with it in my case anyway. My st4 is 8 years old so eroded fuel lines doesn't come as a big surprise. If the new ones last another 8 years I would be happy. Not too mention my st4 didn't get much use in its first 8 years of life having only accumulated 3700 miles by the previous owner so if it sat aroud with a half tank of gas or less I would imagine air on those lines didn't help. I think being submersed is better for them. I also noticed that most of the fuel line posts seem to be from bikes as old or older then mine so age might be the biggest factor. I'm sure crappy fuel doesn't help but maybe just part of the equation.
 

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I have a friend who is a rubber chemist at Minnesota Rubber Company. I related the story of finding the so-called "submersible" fuel hoses in my 1999 ST2 completely destroyed, and he explained in great and unfathomable detail the damage that "fuel extenders" like ethanol can to to the elastomers in rubber hoses. He explained also that the reason for the high price of SAE 30R10 fuel hoses is special polymers which are quite expensive to manufacture.

I don't know when my ST was last drained of fuel and examined, but the fuel filter was a BMW unit, so I know it had been done at least once before I purchased the bike. My hoses at 22,000+ miles were like Silly Putty. The tank was filled with rubber bits, and I could strip the outer rubber covering from the hoses with my fingers.
 

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I also noted that as the "Silly Putty" hoses dried out on my work bench after I had removed them, the rubber basically crumbled and fell off down to the braided core of the hose. Thus, I can see the need to keep the fuel tank full, especially during storage.

PS: Bill, I hope you are on the mend and feeling better. I broke three ribs in November and couldn't roll over in bed without pain for about five weeks. Good luck to you.
 

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It would be interesting to note who is having trouble with their fuel hoses and where they live. Mine seem to be just fine and I live in Texas, land of oil not corn, where I don't see any ethanol in the fuel.
 

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I wrote back to my friend the rubber chemist this afternoon for an explanation of crumbling fuel hoses, and this is his response:

The reason for the destruction of fuel hose in a submersible environment is that ordinary automotive fuel hose is a dual construction component. The outer veneer is made of less expensive NBR (Nitrile Butadiene Rubber), or CSM (chlorosulfonated polyethylene aka Hypalon), or ECO (epichlorohydrin). Depending upon the manufacturer the outer veneer could be any of these. The inner veneer is usually an FKM (fluorocarbon rubber aka Viton). There are several families of FKM that can be considered for use, each increasingly expensive in proportion to the chemical (fuel) resistance and ability to comply with EPA SHED (Sealed Housing Evaporative Determination) requirements. The outer veneer is low cost and designed to provide resistance to the underhood environment. The inner veneer (FKM) is designed for fuel resistance. If a dual component hose were completely immersed in fuel, the outer veneer would be immediately swollen and eventually destroyed. And if the inner veneer were made with less expensive dipolymer FKM it too could be swollen when in contact with the oxygenated (extended) fuels used today. The fuel oxygenates most commonly used are ethanol, methanol, or less common MTBE. Fuels that contain over 10% oxygenate extender are particularly aggressive. And increasing fuel extender increases the aggressiveness of the fuel. Some fuels can be 20% or more; avoid these. In order to achieve excellent fuel resistance for an immersible hose requires that it be made of FKM ($$) through and through. The best extended fuel resistant FKM's are the high fluorine terpolymer types ($$$). So the next time you spend an arm and a leg for a length of good immersible fuel hose you can thank your political representatives and legislators for passing stupid laws regarding poor performing crap extended fuels and creating the consequences (fuel hose and seal problems) that they don't understand.
 

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Still needs a life.
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Discussion Starter #10
Thanks for posting your friend's response. That gives some scientific basis for everyone's hunches regarding ethanol destroying the fuel hoses.

Next question: when/how often should the fuel hoses be routinely relaced to avoid any surprises on the road?
 

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Thanks for posting your friend's response. That gives some scientific basis for everyone's hunches regarding ethanol destroying the fuel hoses.

Next question: when/how often should the fuel hoses be routinely relaced to avoid any surprises on the road?
Not sure scientifically but after reading the above post I can tell you I will be doing a yearly visual inspection minimum. Hopefully can get 3-4 years and I would be happy.
 
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