Charles Smith wrote:

This is a phenomena known as sour gas.  It is caused by the formation of
peroxides in fuel.  The constant recirculation of fuel in the system by the
injection pump not only heats the fuel it dissolves a significant amount of
oxygen into it.  These two factors combine to cause peroxide formation.  It
can be combatted by the use of expensive fuel hoses which have a veneer of
flurorpolymer or HNBR in the inner most tube section.  Besides HNBR, FKM and
THV have all been used very successfully.  Not only will the flurorpolymers
solve this problem, they make the hose very resistant to oxygenated fuel
effects.

Charlie Smith
Cruiser 4021

<<....skip..... I agree with Charlie's comment that if you stay with AVgas
you are probably  okay, it is the oxygenates in mo-gas that makes it hard

on

the epoxies...skip.... >>

3/4/2002

Hello Bill, Below is an interesting quote from the Aeroquip Performance
Products catalog JC125C. The hose elastomers in this catalog are either

AQP

or Teflon.

"A caution about fuel injection. All hose listed in this catalog is

suitable

for use with leaded and unleaded fuel. However, caution must be used in

fuel

injection systems that recirculate fuel. This causes fuel to oxidize which
can attack the hose inner tube. To increase service life, keep the time of
exposure to the oxidized fuel to a minimum. Drain hose line or flush with
original fuel or other suitable material."

Not very encouraging to people who are using engines such as the TCM

IO-240B

which at times are recirculating almost as much fuel as the engine is
burning. On the other hand maybe the engine is giving better performance
because it is burning oxygenated fuel.

'OC' Baker,  Builder of KIS TR-1 #116 4/14/97 - ?/?/?

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