<VV> fuel pump power question

[jim bannister]

You could do i9t the 20th century way with a relay operated by the series
contacts in a three leg oil pressure switch.  The relay stays de-energized
until oil pressure comes up.  You can feed power to the normally closed
contacts from the power that energizes the starter solenoid.  This give you
pump as soon as the engine cranks.  When the relay picks, it feeds ignition
power to the pump via the Ford crash switch.  No toggle switch needed.
Everything automatic.  To do it the 21st century way you'd need a
micro-processor.
jim

-----Original Message-----
From: VirtualVairs [mailto:virtualvairs-bounces at corvair.org] On Behalf Of
Sethracer--- via VirtualVairs
Sent: Saturday, March 14, 2015 1:58 PM
To: rmurray at pittsburghpenguins.com; virtualvairs at corvair.org
Subject: <VV> fuel pump power question

Rod asked: 

Seth in  this case does fuel simply flow thru the electric pump when it's
not  on?
The original question was for a replacement pump to be mounted near the
tank. I was just addressing the wiring of the pump power feed - excluding
either  a shock-opening switch, as used on many Fords, and/or an oil
pressure - closing  switch, which many add to prevent fuel from flowing if
the engine has stopped  turning. If a toggle switch is wired as shown below,
the center position of  the switch will keep the electric pump from running
at all. 
Closing the  switch to the latch side will provide ignition switched power
to enable the  pump (while the ignition is on) and pushing the switch to the
momentary  side will allow the pump to push fuel into the carbs - with the
ignition off  - for as long as you are pushing the toggle to that position.
A shock-switch could be added anywhere in the "Out to Fuel Pump Power"
circuit out to the pump. It will have to be manually reset when needed.  The
oil pressure cut-off should be in the "Ignition switched 12 Volts  In" feed
into this switch. The momentary position on this switch could  then be used
to fill the carbs after a long "sleep", even if oil pressure  was not yet
present. 
 That makes for easier starting. 
 
And for Rod's specific question. It depends on the pump. Many pumps will
just let fuel pass through when they are not turned on. Some can act as a
positive block for flow. You would have to check, or ask for advice on a
particular brand/model. That is if you are retaining the original mechanical
pump. - Seth
 
Personal Note: - Rod - The Sharks could sure use your help!
 

 
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