maestro1024

I put on an electric fuel pump and wasn't sure where the best place to get power is. I tried a post on the distributor. But I want some where that has power as soon as the key is turned over. What is a good place?

To test the fuel pump I hooked it up directly to the battery. I expected a steady stream of fuel but instead it was in bursts. Should it be a stream (And I have something else wrong) or is bursts ok?

Thanks to all the people and their great help on this site.

ozarks06

Electric fuel pumps are designed to push fuel not suck it (which is probably why it spurts). You should put it at the tank, run a 10 ga wire to it (with a 20 amp fuse - a lot more current than the distributor circuit can supply), controlled by a relay. You should also put an inertial cutoff switch in the power circuit so it doesn't keep spraying fuel after an accident.

69mach1377

Mine is hooked up to the starter solenoid IIRC. It came that way when I bought it 21 years ago...

maestro1024

@ozarks06- Thanks. Maybe I missed it but if I it back by the tank where do I get power from back there.

Also, If I put it back at the tank do I put it right at the tank? Between the tank and the metal fuel line is a several inches of rubber line. I could put there I guess.

kalli

any electric fuel pump _has_ to be mounted directly at the petrol tank. as ozarks said they are useless at sucking fuel. I know it's probably not how you planned it, but I was hunting plenty of problems (leaning out at high revs, dangerous) because the pump could not supply the demand. there is no exception to the rule. not even a 140gph electrical pump will do that (gerotor and stator design).

Once you have mouted the pump in such a way that it sitting that petrol will flow into it on the 'in' side you power it with a relay.
The pump gets power from the relay and the relay gets the signal from ignition switch or coil. The 'I' port at starter is only then a good idea if that is actually hooked up to the coil. as otherwise you only have power during crank. The source should be 12V switched. so a stock coil might only get 8V when the resistor is still in place. It depends on the relay if it will switch then or not.
So from all this an electric fuel pump is a lot of hassle for no gain on a carbed engine.
I put one in because I believed I had no excenter at cam to operate it and thought electrical pump will be easier than just putting one in. I think with the hassle I had and experimenting I would have just been better off with a manual pump.
However it has advantages. You can check on fuel pressure with engine off. fill the bowls if neccessary and check for leaks ;-)

Kalli

maestro1024

What kind of "inertial cutoff switch" would you guys recommend? Would you use one off of a newer mustang or are there generic ones (I am using a mr gasket pump if it matters).

Also, are you guys suggesting I run power from the distributor all the way back to the tank? Isn't there power on the tank? I was thinking I would just splice that off to power the pump (with a fuse between them).

ozarks06

I got an inertia switch from the junkyard from a late-model Mustang but you can probably buy one at the auto parts store. You will need a hefty line (10 ga.) directly from the battery (through a 20-30 amp fuse) to a relay in the trunk. The other post of the relay contacts goes to the pump (and other side of pump grounded). You control the relay with a smaller wire (only about .1 amp to run the relay coil) from the ignition switch, THROUGH THE INERTIA CUTOFF SWITCH, to power the relay coil (other side of coil grounded). That way the ignition powers the relay coil (and power is cut in an accident - put the inertial cutoff switch in the trunk) when the ignition is on. Here is a very simple schematic.

ign switch ------> inertial cutoff switch -----> relay coil --> ground

battery + ------> 20-30 amp fuse ---------> relay switched / relay switched ---> pump+ pump- to ground