This is what I have done. I attached the fuel pump to the frame next to the gas tank. I grounded it. I ran the positive to a newly installed fuse box. I put power into the new fuse box with a ten gauge wire. I connected the wire to the second prong on the solenoid. The one next to the prong that has the positive go to the starter. The prong I connected it to provides power when the the ignition is on. The motor is not in the car, but the elctrical is in. Here is the issue: When I put the ignition forward the pump runs (I got it flowing into a gas can). When I put the ignition all the way forward (like I am starting the car) you can hear the pump run faster. Is this a problem? What is a solution?
IMO it's a problem. You don't want anything else running when your starter is going... other than ignition. Your starter already draws alot of amps, then even more when hot. For the most part, it won't hurt anything to have this going on, but one day, when you least want it, the starter or battery is going to be on the edge. That extra couple amps the pump is pulling when not needed will be a 'deal breaker'. You don't even need the pump running with the key. They sell oil pressure sensitive relays to only run the pump when oil pressure is up. That way you aren't forcing fuel to the carb when the engine is not using it, and if your oil pump ever dies (and you don't notice the gauge drop), the gas flow will stop, keeping you from burning up your engine. Dejavu... I just recently made the same post. Maybe to one of your threads! Oh well. Good luck Dave
The oil pressure switch is required by DOT and UL to prevent an engine fire from being fueled by gas if the engine is not running. If your pump speeds up when the switch is at the start position then you are running your pump off the resistor wire for the coil. You need to find another wire to run your new fuse block.
I don't know of anyone who does it for DOT... However, I remember my dad's Holley blue pump on a manual toggle switch... That thing could over pressure a Holley needle in a heartbeat if you weren't careful or your needle got some junk in it. Then the carb looked like a fountain if the pump was running and the engine cut off or the switch was flipped before starting the engine. I went through a fuel pump issue that I set the floats higher than I should have, before I knew the problem. When I got the problem worked out, I forgot I set the needles way high... Next time I started the engine, I got the gas fountain out of the vents and then my car caught fire! I burnt my day old MaverickMan carbon fiber hood... I know my 'problem' wasn't related to the powering of an electric fuel pump. I was just noting that an electric fuel pump that is allowed to run when not needed can cause the same consequenses that I ran into with the fuel overflow and flash fire. I was lucky that CF hood was shut when the fire flashed. If it was up, the massive fuel 'fountain' would have got enough air that my car would have gone "fully involved" before I got the extinguisher.
The oil switch has three terminals on it. C (common) goes to the pump +; NC (normally closed) goes to the starter solenoid (starter BIG wire); and the NO (normally open) goes to the ignition side of the switch. That way you get power to the pump when cranking, as soon as oil pressure comes up it switches to the ignition side of the switch. (NOTE: do not hook the fuel pump to the coil +; that will rob power from your coil, find another switched source on the ignition side of the switch (one without a resistor))
You don't need the fuel pump when cranking... That's what your fuel bowls are for. They have plenty of fuel to start the car.
Try starting an engine that has been sitting or six months without the fuel pump working! The fuel bowls can evaporate or otherwise lose fuel over a short period of time. It may not be necessary every time but when it is needed the pump has power. NOTE: The fuel pump will only pump when there is room for the fuel - otherwise it just goes into relief.
Very true. I just have seen the potential for problems when you run an electric pump without a full-on return line. The bypass inside the pump, and carb needles aren't always trustworthy in my experience. Also, one could use the oil pressure system for safety, and hook up a manual ON toggle for convienence when the car has sat long term. You gotta remember though, in that case, fuels today don't last as long as they used to. Gas turns to terpentine much faster today. This means if your car sits longer than a few months with gas in it, you got far more problems than if the bowl is empty.
