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wrongsideup

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Question: I have a '57 chevy with electric fuel pump. The pump is not installed as I would like. Now as soon as you turn the ignition switch on the fuel pump energizes.
The problem with that is if you are just sitting in the car with it off and want to listen to the radio you cannot because the fuel pump runs at the same time. It's as there is no "ACC" position on the ignition switch. Or it's "ACC" and "ON" is just one position. I can't find anywhere an internal diagram on the switch to see how it works. I see in Danchuks catalog there is "update" replacement. They do not show how its different from the original, just that you cannot use it with factory wiring. I bought an oil pressure safety switch and a relay to rewire this pump problem. Now I do not know how to correctly wire this circuit through the ignition switch to the relay. Any help would be appreciated...
 
#2 ·
If you have the original or Factory Fit harness, you are using the original switch and it does not have an ACCessory position....Just put in a separate switch and relay between the power source and the pump.
 
#4 ·
Hope to explain this correctly because it's been a while. When I put an electric fuel pump in my gasser, I ran it through a relay. I didn't want to burden the ignition switch with more current. Also in the line I put a toggle switch. Reason being, I wanted to control the on/off of the fuel pump w/o benefit of having the ignition switch on and the pump running. If I wanted to work on the power windows, listen to the radio or do anything electrical, I wanted to avoid this issue. That's what I think I recall, Carmine.
 
#7 · (Edited)
Wire it through a SPDT relay to the oil pressure light sender
You'll need to wire a relay via the oil pressure sender [which grounds] like this

Post # 30 from fuse box [switched side]
Post # 85 from fuse box [post 30 & 85 can be bridged ]
Post # 87A to fuel pump
Post # 87 not used [the relay switches to this post when the Ignition AND oil light is ON!]
post # 86 to oil pressure sender [which grounds]

With this method when the oil pressure is UP, the sender breaks the ground and switches OFF the relay, which defaults over to Post # 87A [connecting to Post # 30] With the Ignition Off there is no power feed to the relay.

You can Also connect the ballast resistor to Post # 87A , this will save the points [The ignition will require oil pressure]
The engine will still have ignition for starting via the wire from the "R" post on the starter solenoid to the coil

If you want a bypass switch [to prime the pump] , you need a button to break the ground circuit [from post # 86]

So you can use a brake switch with cruise control
Post # 86 goes to one of the cruise control terminals, the other terminal goes to the oil pressure sender.

With the key on, the fuel pump will prime with your foot on the brake, and stay on with oil pressure.
 

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