The fuel pump is shut off by closing the valve between the tank and the
fuel pump . Your problem sounds like the restricter is missing in the
outlet fitting of the pump allowing too much fuel to the tank. Glenn
Putnam
On Apr 25, 2009, at 5:36 PM, John Roach wrote:
Bert,
I guess I missed something in your message. What kind of a fuel system
do you have that allows you to "turn off the fuel pump?"
Most Coupe fuel pumps are mechanically driven by the engine and the
only
way you turn them off is by shutting down the engine and stopping the
prop.
I also don't understand how you can hear the fuel flowing back down to
the wing tank when you over fill the header tank. The only time the
header tank fills is when the engine is running and in most Coupes,
when
the engine is running you don't hear much else. Are you filling the
header tank from a fuel source on the ground? If so, that might be
your
problem. If the header tank and the wing tanks are brim full on the
ground before the engine starts, there is no place for the excess fuel
overflow to go when the engine starts. In the "normal" situation,
there
is no need to ever add fuel to the header tank as it fills itself as
the
engine runs and any excess is returned to the wing tanks. If the
system
is completely full on the ground, there is no room in the system for
the
overflow when the engine starts, the fuel has to go some place. I
guess
the foot of the left seat occupant is as available as any other place.
John Roach
N 2427H
Bert wrote:
>
>
> I have presented this problem before. Several suggestions were put
> forth. However, the problem presists. In a nut shell:
>
> - every flight leads to an eventual high volume leak of fuel into
the
> cockpit generally over the left seat occupants feet.
>
> - turning off the fuel pump will stop the leak.
>
> - the system has been pressure tested twice, no leaks found.
>
> - the aircraft has had a fuel 'smell' for sometime now.
>
> - installtion of a new fuel filler cap (with glass covered fuel
level
> indicator) solved the odor problem.
>
> - the new cap has a NEW gasket.
>
> - the caps airvent seems the only place fuel can exit the header
tank.
>
> - the gasket at the at exit of the filler tube through the cowling
is
> probably as old as the plane (1946)
>
> - best idea is, the system builds up pressure and forces fuel out
the
> air vent, which then is forced by the in flight airstream down and
> under the cowling where it eventually flows over the header tank and
> onto the left seat occupants feet.
>
> - the overflow plumbing seems to be in working order. You can hear
the
> fuel flowing back down to the wing tank when you over fill the
header
> tank.
>
> - fuel exiting the airvent is not visually apparent during flight.
>
> - simply replacing the gasket at the filler tube/cowling would stop
> the fuel from entering the cockpit --- but not the actual lose of
fuel
> in flight
>
> - anyone want to suggest a fix? Turning off the fuel pump and never
> allowing the header to fill itself works, but is obviously not a
fix,
> just a work around.
>
> Help --- anyone, Please.
>
> Bert Hampton
>
>
