CK5
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I’m really unfamiliar with these tank selectors, I have never seen one or worked on one.

If your truck didn't have it from the factory you will need to cut a rectangular hole in the dash and add a filler on the other side of the bed and wire it all up, not exactly easier than putting the tank in the back.
 
If your truck didn't have it from the factory you will need to cut a rectangular hole in the dash and add a filler on the other side of the bed and wire it all up, not exactly easier than putting the tank in the back.
I was thinking about sense it’s a 20 gallon tank to use a short filler and stick the nozzle in the wheel well. Also for switch I thought I could program the pro dash to handle that.

@mrk5 that is very helpful, which part number do you have?
 
The valve needs a momentary power signal to actuate the change in position. This is why the factory switch has a note on it "Depress Fully" . Once you release the switch, the power delivery stops. It flips which direction the valve spool is moved inside the switch.
I installed one in my old '68 decades back. But I was able to find new parts and junkyard parts to do then.
 
The valve needs a momentary power signal to actuate the change in position. This is why the factory switch has a note on it "Depress Fully" . Once you release the switch, the power delivery stops. It flips which direction the valve spool is moved inside the switch.
I installed one in my old '68 decades back. But I was able to find new parts and junkyard parts to do then.
Does the switch have both momentary and constant poles? Or does the valve switch the sending unit too? I don't remember but it needs to be switched somehow because the gauge stays on whatever tank you switched it too...
 
Does the switch have both momentary and constant poles? Or does the valve switch the sending unit too? I don't remember but it needs to be switched somehow because the gauge stays on whatever tank you switched it too...
I was hoping to do the fuel level sensors into the Holley having 2 gauges at all times but this would work to.
 
Does the switch have both momentary and constant poles? Or does the valve switch the sending unit too? I don't remember but it needs to be switched somehow because the gauge stays on whatever tank you switched it too...
That part is fuzzy in my memory. I don't remember if the sender wires went to the valve or the switch.
I would have to dig out a manual to look.
 
@Babaganoosh, the order confirmation email says 42-159P.

My switch didn't act like a momentary, it was just a 2 way switch. I changed it out for a nicer 3 way rotary switch that was ON-OFF-ON. This is might be a difference with TBI trucks.

The sending unit switches in the tank selector valve. Here's the factory wiring diagram below. The pink wires are fuel level. The gray and tan wires are fuel pump power.

Screenshot_20240504_203410_Adobe Acrobat.jpg
 
That part is fuzzy in my memory. I don't remember if the sender wires went to the valve or the switch.
I would have to dig out a manual to look.
I don't remember either and I tore it out when I converted my factory switch to a transfer pump. If I momentarily press the button, it just switches the gauge to see the tank levels. If I hold it down for two seconds, then it starts to transfer the fuel until one is empty or the other is fill, whichever is first.
 
My 72 had a switch on the dash that controlled what sending unit the gauge read and a manual valve on the floor next to the drivers seat. They don't necessarily need to both be the same switch. Seems convenient but there were many times that I was unsure of how much fuel I had and would just switch the dash quick to double check the level in my other tank and wouldn't necessarily want to actually switch what tank I was pulling from. There was also a 3rd port, I'm assuming the truck at one point had 2 saddle tanks as well as the in cab. The third position essentially could be used as a fuel disconnect anti-theft position. I actually had a friend driving it and he ran out of gas in the main tank and saw the dash knob and switched it to aux and the gauge went up and he still couldn't start the truck. I walked up and switched the valve as I climbed in the truck and it fired right up. :D
 
That should work, that's the factory 6 barb type. Just use the right hose and clamps for EFI. Also confirm they are still rated for 65 psi, not that you need all 65 psi.
 
Got some new parts coming soon...


fuel tank brackets for the 20 gallon aux tank
New trans cooler. https://derale.com/product-footer/54010-detail ( probably going to use my existing as a engine oil cooler

Also the crossmember needs a slight modification to work at full droop, bummer but oh well that's what happens when it's all custom.
 
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