Technical Fuel Pump Wiring Diagram

Hey guys. I've been looking to make my fuel pump a little more safe as it is currently activated with just a toggle switch. Some have recommended a Ford crash sensor switch (too much for me.) What do you think about the following diagram which routes it through a pressure switch first? I see in a past post @squirrel and others mention doing that.

Also, is it going to have problems with a dry start -- when there is no fuel in the bowl and not enough pressure to activate the switch? Could that be alleviated have a wire from the starter to the relay, so that when cranking it activates the pump?

Credit for diagram goes to: roadkillcustoms.com - @RoadkillCustoms

 

You can add a push button to run the relay whenever you want....

I haven't had much trouble with starting, using the pressure switch.

 

That pressure switch I believe is a roll over switch in case of an accident so the fuel pump stops running when there is no oil pressure. All new cars run them and mandatory for us down here with our builds. As long as you have oil pressure the pump will run, the moment you don't, well it stops.

 

Pressure switches have been used for a long time. Chevy Vega had one so the motor would not crank until it recognized oil pressure.

 

You could also use the safety relay from a propane powered vehicle- they have a +12volt input, ground, points input and 12 volt output. Works like this- turn on ignition, (which is connected to +12volts), box looks for points pulse. If the points are working (engine running), it gives you an output of 12 volts (which you feed to your fuel pump). If there is no points input pulses detected, i.e. your motor has stopped, the output to your pump stops.
I have used these many times, and pick them off cars at the junk yard.
It will also give you an output for a couple of seconds after you initially turn on your ignition , then turn off. Very handy when you want to prime the carb.

 

Why is the Ford sensor "too much" for you?

Know any one that does the Demo Derbys and they are free, one of the first things they remove when prepping a Ford product, last I checked they weren't all that pricey new.

We put one in my buddy's lakester harness between the ignition switch and relay that controls everything. Anything happens and no power to everything, no wait for the engine to quit to shut down the pump. Mounted it with the reset button on top within easy reach in case the car[with stiff suspension] hits a sharp bump on the course. Witnessed a roadster driver have to abort a run when that happened and his switch was mounted out of reach...........

Ed

 

Would not crank, or would not start? To me, and I assume most folks on the board, cranking is simply the starter motor turning over the engine.

"Gentlemen, crank your engines!"

 

I think there are more potential "incidents" that could happen that will cause the engine to stop, and you don't want fuel pressure, than just rollovers. That's why I use that 3 prong oil pressure switch, not a rollover switch, to run the pump on my hot rod.

When the engine quits running, I want the fuel pump to stop, also.

 

Nothing wrong with the belt and suspenders approach to keep the butt covered, run both switches in series between the ignition switch and relay.

Ed

 

They aren't really "Roll Over" switches - they are inertia switches. They work by a small weight inside that is spring loaded, it the vehicle experiences a certain 'G' load the weight overcomes the spring and trips the switch - so that could be an accident as well as a roll over. They have a reset button so that if a huge pot hole or something sets it off you can push the button and continue on.

This is an interesting one that reads off the tach signal from the ignition , but primes the pump for 3 seconds on start up. http://www.revolutionelectronics.com/Fuel_Pump.html