You are making this way to hard when the factory stuff to do it proper is out there. You're revised wiring I'd scrap that. I could wire it to work. I could tell you how to do it. But you still won't have any control of fuel returns. On the first diaghram I wrote you,you hadn't informed any of us you had dual tanks so I didn't write it for dual tanks. Then you got part of a wiring schematic from YouTube.That if you use it the way you wrote it only 1 tank will work,and that's just a maybe,and it will run anytime the key is on ,which is wrong.You really need to do this Like factory,they took everything into account. If you insist on rigging it here's a diaghram that will run both pumps and the fuel gauge and the pumps will only run when the engine is running. I can't say that one fuel pump or return line or both won't overfill 1 tank by pushing all the fuel from the running tank into the unused tank. That's why the factory used a valve,not just running 2 pumps. They were smart enough to make 2 pumps and a gauge run,they thought controlling fuel flow was more than just turning right or left pump on. Get 2x5 prong relays 1x2 prong normally open Oil Pressure switch typically used to control the choke on a C10 pickup. Connect 1 leg of the OP switch to battery positive with a fuse. The other leg to terminal 30 on the FP relay. #87 on the fuel pump relay to one fuel pump 87A to the other. 86 to ground#85 to a powered selector switch. Second relay #30 to dash gauge #87 to one tank sender 87A to the other #86 to ground #85 to your powered selector switch. If you want a prime circuit let me know. That will be another chapter.
