So my fuel tank is sound, as I had it coated back in the '90s and it's never sat without running and allowed the gas to go bad. But it's getting some surface rust on the outside so I'm gonna drop it and paint it, since now it happens to be empty anyway so it'll be light.
I've already got an inline electric fuel pump, wired through the oil pressure switch for safety, I don't miss the mechanical fuel pump foibles at all. Now it's almost 2025 and I'm thinking ahead to fuel injecting that Cadillac 500 so maybe it won't drain the fuel tank quite as fast. What I'm wondering is, if I mount up an in-tank fuel pump while I've got it apart, is there a reliable regulator that I can get which will bring the modern pump down to the 6 PSI required for the Edelbrock 4bbl it's got now? So I could just drop the tank once, then remove or turn off the regulator later when I got the EFI which requires 40-50PSI. Alternatively, is there a low pressure pickup pump I could use for now, then put the high pressure boost pump in later? That's what Cadillac did with their analog EFI system back in the '70s. Then the two pumps worked together to burn up that single tiny fuel pump power pin on the ECU, until you made the relay hack to allow only the small current switching to happen inside the ECU.
I'm already in the system to replace the rusty original steel hard line, so will be good to go there. All new steel hard line from tank to engine bay. So I can either go with high pressure in-tank pump with a pressure reducer, or low pressure pickup pump now and high pressure boost pump later.
If you eventually go with EFI you probable need a return line to dump the extra fuel from the high pressure pump. You could install the high pressure pump on the regular line in the tank, use the new return line for now with the low pressure lift pump and just rig the plumbing in the engine compartment to use either line as needed.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
I just made the new 3/8" main line today, so I'll go get some 5/16" steel for the return. Will do all the plumbing along the frame and to the tank now, so later on I won't have as much work. Holley makes a 7psi return style regulator for in tank pumps and a carburetor, it's $65. So if I just rig that up now, then when I EFI I can remove it and use the return line from the new system. Might as well make it easier now, while I've got it apart anyway.
Here's the new line I bent up using the old one as a pattern. Felt good to use my old '90s era tools from when I was a professional auto mechanic.
