Thinking this through and wondering how to best wire the electric fuel pump I am using. Do you wire it so that the pump is on during starting or just in running position? Trying to picture how you ensure to have the pump run during both without shorting the two sides of the key switch.
I use a relay that runs the pump from the starter circuit when cranking and then switches to ignition voltage once the engine starts and also run it through an oil pressure switch so it will shut of if the engine is not running of if you loose oil pressure pressure.
I use a 3 pin oil pressure switch, made for the job, it connects to the starter circuit, ignition circuit, and pump. When there's no pressure, it connects the starter wire to the pump, when it gets pressure, it connects ignition to the pump. The terminals are even labled S I P http://www.rockauto.com/catalog/x,carcode,1056664,parttype,4588
If you are talking about a hotrod with a carb, just hook it up to the run terminal. Turn the key to run, let it click until it slows down and then start it up. Not complicated at all. If it's a modern fuel injected in tank unit...get a manual.
Is there anything Squirrel doesn't know? http://www.misterfixit.com/fuelrlay.htm You'd be crazy not to run it using that oil pressure switch he's talking about.
Saftey First! You should run a relay, and an oil pressure saftey switch is a good idea. You only have to be on fire once to take saftey seriously.
and no reason to spend stupid money on these relay kits you see. JC whitney or Pepboys sell generic style relays for $7.00 that work great.
My universal fuse block/wiring harness came with a relay for the fuel pump. I just wired in a switch on the dash marked"fuel" to energize the relay.
i wired mine so the pump is powered when the ignition switch is in the on/run position (push ****on start). i put a toggle switch under the dash so i can cut power to the pump. i like being able to control the starting, ignition, and fuel circuits separately. good theft deterrent too.
Hey, for these 3 pin switches, are you also running a mechanical oil pressure gauge? I'm just thinking how I want to connect it all. This on a SBF btw.
i did pretty much the exact same and with the same thought about being a good anti theft. my toggle switch is easily reached from the driver seat without being readily visible. i use a relay to run the pump that gets powered with the key in run and crank positions. i use the toggle switch to kill the pump when i want the key on without the pump running.
I also add inline an Inertia switch, found on most Fords. Shuts off pump if you get ***-packed by some texting teenager
A lot of the fellas run a relay. if you have a carb you don't need it to run while you are in the start mode you should have plenty of fuel in the bowl to fire it off. I never run my pumps off the ignition switch I always run them off a toggle. If you don't want to buy an expensive relay or relay kit you can use a Ford starter solenoid for a relay. Works like a champ.
Bought the switch today. I'm a little dense here. Starter circuit vs ignition. So the S is coming from the key switch run position, right? Then the ignition goes on to the distributor? P to the pump relay right?
S goes to the wire that connects the ignition switch Start terminal to the starter solenoid. This is what provides power to the pump while you are cranking the engine to get it started. I goes to the wire that provides voltage only when the key is on. This is what powers the pump most of the time. P goes to the pump or pump relay
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