Hey all. While going through fixing a whole handful of wiring issues, I’ve been trying to figure out what signals the fuel pump (in a 1979) to turn off after a certain time with the key in the “on” position (when it primes the fuel lines).
My problem is that the pump decides it’s not gonna shut off after a few seconds—it just keeps going. Just about everything else in the car works just fine, so I’m fairly confident my voltage regulator is fine. One thing to note is that the car (a ‘79) came with a late-model alternator (internally regulated) so it’s only grounded and doesn’t have the two-prong connector hooked up, because the car also came with an external regulator. I’m still waiting for the stock ‘79 alternator to arrive. I’ve had some voltage issues with the fuel pump (mainly corrosion), but now it gets justttt about 12v out of the 12.3v or 12.4v it should be seeing, so it kicks on but sounds a little shaky lol.
Another thing I’ll mention is that I have zero fuel in the tank, pump, and carb; it’s bone dry, so idk if that is causing anything, which I doubt, but it doesn’t hurt to mention I guess
One last thing to note is that it’s an “aftermarket” replacement pump, but it’s supposed to be an OEM replacement, so theoretically it should be compatible.

Anyway, I guess I just need to know what tells the pump to shut off and when, because then I can probably figure it out from there

If you do need any more clues/info about the car though, just let me know. Thanks

 

its really simple, pump runs when you turn the key to the ON position, turns off when you turn the key back to OFF

 

Ohhh okay, thank you! 😅 I can’t believe it’s that simple lolll. Thank you again!

 

Yeah, I don't know when they controlled the fuel pump from the emissions computer, but it was definitely after 1981.

When I got.my '81 and the fuel pump wasn't working, I figured okay, it's because the emissions computer is turning it off... After tearing the carpet out to get to the computer to unplug it (relay is a NC relay, unplug computer = full-time fuel pump) I discovered that Mazda just ran the pump to the ignition switch.

Then later I discovered that I forgot to put the evaporator drain back through the firewall. D'oh!

 

My 83 GSL fuel pump stays on with the key.