I have a 1979 K25 and we are about to do an FiTech unit on it. I’ve purchased 87 gas tanks, 87 sending units, aeromotive in tank pumps, the 87 switching valve with its pigtail harness and the 87 switch for the dash. What relay do I use to wire the pumps so they turn on and off when each tank is selected?
Just a heads up to research... 87 switch valve was designed for 10-15 psi pumps. Efi needs approximately 60psi, so hopefully it’s up to the task. I’m not sure, just making sure you are. I used a different switch setup altogether. However, I’d assume that the switch has a single power supply 12vdc+ that gets directed to the selected side. If that’s the case, only one relay is necessary on the hot(line) side of the switch. Then it’ll only power up the selected pump. Otherwise, the two load sides of the switch can act as triggers for individual relays. Sorry I can’t provide pictures. My sniper has a built in relay for the fuel pump, so I didn’t have to do any of this.
here the 87 diagram. the wiring is different than your 79. if you can get the switch and harness from the later version it will help you might have to make a custom harness. ignore the fuel module part of the diagram but the rest is accurate to your project..
I replaced mine with a newer valve and it said it was rated to 65 psi also. welcome, I would wire the relay in the same way the 87 did so it only uses 1 relay and switches the power to the desired tank.
Or I have factory style conversion kits for this type of swap-with or without an OEM supplied Pollak 65 psi valve.
I prefer to use 2 pump relays so if the event of a relay failure, you can still switch tanks and run on the other to get where you’re going.
