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Ethanol and your carburetor.


It’s a good chance that the fuel you buy at the filling station today is E10 gasoline, meaning it contains 10% ethanol and 90% gasoline.  Ethanol laced fuels are not going away, so we need to adapt our older carbureted cars to run with today’s new ethanol enhanced fuels and understand how its affects the fuel system.  Ethanol, even if only 10%  is very hard on our classic cars.  The ethanol has disastrous effects on rubber fuel system components, especially rubber accelerator pump cups, carburetor needle and seat valve tips and rubber fuel lines.  This applys to automotive carburetors and marine carburetors.


Accelerator Pump Cup-

Its probably the hardest hit component; we get more inquiries regarding failed carburetor accelerator pumps than any other issue.  The ethanol swells the rubber cup causing the cup to stick in the bore and fail completely.  .  The solution is to use a new ethanol compatible accelerator pump cup.  


Be aware that not all "Blue" ethanol rated pump cups are equal.  We have switched to firmer pump cups as we have seen issues with some of the blue pump cups out in circulation.


Needle & Seat-

Rubber tipped needle and seats do not react well to ethanol, they get soft and can deform and erode.  The solution is to use one of our viton tipped needle & seat assemblies.


Rubber fuel line-

All flexible rubber fuel lines should be replaced with ethanol compatible fuel hose.  We offer premium ethanol compatible fuel hose in ¼”, 5/16” and 3/8” sizes.


Other Carburetor Issues-

Be aware that ethanol tends to retain water and this can lead to corrosion of metal carburetor components.  This is especially hard on marine carburetors.

E-10 fuel will cause an engine to run slightly leaner than 100% gasoline and ethanol is less-efficient than gasoline.  If you notice light throttle surging you will benefit by richening up the cruise/light throttle air/fuel ratio.