Now general warnings for retrofits was Re: Adding a gas tank return

[Shannen Durphey]

Fran and Bud wrote:

> 
> I have had good luck for years in adding things like outlets or returns by
> cutting a 2 1/2" or 3" disc from some heavy sheet metal with a hole saw and
> then brazing tubing or fittings into it and drilling a 4 to 6 hole pattern
> near the outside edge.  It can then be fastened over a small hole in the
> tank using cork or neoprene gasket material and bolted down with 4-6 self
> tapping sheet metal screws.  If you want to get fancy you can use threaded
> inserts and machine screws.  In any case all of the fabrication is external
> to the tank except for cutting the extra hole in it, and vacuuming out the
> shavings.
> 
> Bud
This is not an unusual approach.  There is another consideration when building
an efi system including a tank not originally designed for it.  

A return type efi system will transfer heat to the fuel in the tank.  The fuel
will expand and produce vapors as a result of this.  The tank should be
positively vented in these situations.  If a sender/tube/whatever has been added
by the method mentioned above, it is very very likely that fuel vapor will be
forced out of the tank around the screws and gasket.  Do not rely on a pressure
release cap to vent the vapors.  These caps can vary significantly in their
"release pressure."  4-5 psi pressure in the tank can easily force fuel vapor
out around a home made sender.  Better to be cautious (and responsible) than
sorry.

Shannen

----- End of forwarded message from owner-diy_efi at diy-efi.org -----
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org