[Rhodes22-list] Another ethanol-related failure point

[Michael D. Weisner]

John,

Sounds like you identified another problem area for ethanol fuel.  The exact 
problem that you discuss has been plaguing the classic car (60s & 70s) 
folks.  Many of the old GM cars (GTOs, 442s, etc.) that used a Rochester 
quadrajet carb had the same problem when run on E10 fuel.  The problem was 
traced to a rubber tipped inlet needle valve and a black rubber accelerator 
pump cup.  The solution was to replace the needle valve with a Viton tipped 
product (easy to identify, Viton is shiny, rubber is dull) and the 
accelerator pump with neoprene (usually blue).  Some folks say they solved 
the problem by adding Marvel Mystery Oil in the ethanol gas blend.  It's an 
interesting fix if it works.  Maybe that's why my old Suzuki 2-cycle is so 
reliable, even on ethanol fuel.

Mike
s/v Shanghai'd Summer ('81)
Nissequogue River, NY

From: "John Lock"  Thursday, August 13, 2009 3:27 PM
> About 2 weekends ago my trusty Nissan 8hp outboard quit while we were
> motoring home under windless skies.  Fortunately not too far from home
> and we got a tow in.
>
> Fiddled with it a while and could get it to run for 15-30 seconds or
> so and then it would just die.  Checked tank vent, filter, fuel line
> and confirmed that fuel was flowing freely all the way up to the
> carburetor.
>
> Having a little experience with outboard repair, I took the carburetor
> off and dismantled it.  On closer inspection I realized the float
> valve was sticking up - in the closed position.  So, it would let fuel
> into the carburetor until it closed and then never opened again.  The
> engine would use up what was in the float bowl and quit.  A couple
> raps on the side with a screwdriver would sometimes knock it loose and
> let fuel come in again.
>
> So... the problem was obvious but the cause was more insidious.  The
> float valve (also called the needle valve) has a rubber tip that seals
> the fuel inlet opening when the float rises and the carb bowl is
> full.  But ethanol had degraded the rubber tip, making it soft and
> sticky.  The float would push it up in the valve chamber and the
> rubber would deform and stick in the narrow opening.  So, no more fuel
> coming in until it got knocked loose again.
>
> Strangely, the other rubber parts seemed to be in good condition.  But
> I ordered a carb kit and replaced everything anyway.  Now tt's back to
> its usual smooth running self.
>
> Another thing to check if you have fuel-related problems...
>
> Cheers!
> John Lock
> ~~~~~~~~~~~~~~~~~~
> s/v Pandion - '79 Rhodes 22
> Lake Sinclair, GA
> ~~~~~~~~~~~~~~~~~~
>
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