Here's how I go about adding a safety oil pressure switch so the pump only
runs when the ignition is on and the oil pressure is up. Use an oil
pressure switch from a Chev Vega. You will also need an 1/8" brass tee and
maybe some short pipe nipples, etc. to plumb both the switch and the guage
or guage sender. These switches are available from most local auto parts
stores. Three part numbers: NAPA (Echlin brand) p/n ECHOP-6610 or Standard
brand p/n PS-133 or Delco PS-9. While at the parts store, also get a
standard sealed-beam headlight 3-prong socket connector. This connector fits
the new oil pressure safety switch. The switch is about $9 and is cheap
insurance.
The switch has three prongs marked "I", "S" and "P." When there is NO oil
pressure, the "S" and "P" are connected. When there is oil pressure, the "I"
and "P" are connected.
The "I" wire is connected so it receives 12 volts, fused, when ignition
switch is on.
The "P" wire goes up to the pump or pump relay depending on the pumps
current draw.
The "S" wire goes to the starter solenoid "S" terminal to energize the pump
during cranking.
The negative terminal of the pump is grounded.
How does it work?
The "S" wire runs from the pick-up terminal of the starter solenoid which is
energized only when the key is turned to start the motor. The current goes
through the normally closed (at rest) contacts of the oil pressure switch to
the fuel pump (between contact "S" and contact "P"). When the engine starts
and the oil pressure rises, the switch transfers, causing current flow from
the ignition switch (contact "I") through the transferred switch contacts to
the fuel pump (contact "P"). As long as oil pressure is maintained and the
ignition is on, the pump keeps running. If oil pressure is lost from an oil
pump failure, or a major short develops, the engine automatically shuts
down.
Mark Sedlack
Cuyahoga Falls OH
66 1600 http://home.neo.rr.com/mark2000/images/datsun1600/
77 280Z http://home.neo.rr.com/mark2000/images/datsun1600/Z.htm
----- Original Message -----
From: "John F Sandhoff" <sandhoff@csus.edu>
To: "Daniel Neuman" <dneuman@quark.sfsu.edu>
Cc: <datsun-roadsters@autox.team.net>
Sent: Friday, June 20, 2003 8:33 PM
Subject: Re: elec fuel pumps and fuel pressure reg.
> > I want to install an elec fuel pump and pressure reg on my car.
>
> Don't forget the cutoff switch - either an inertial unit, or one tied to
> the oil pressure line (Holley has a good one that runs the pump
> while cranking).
>
> Someone should write an FAQ on this topic :-)
>
> -- John
> John F Sandhoff sandhoff@csus.edu Sacramento, CA
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