Another fuel selector valve question

[mxer147]

EFI now carbureted using a noisy Holley red pump pulling from dual tanks with six port selector valve. This evening I was going to adjust noisy rocker arms so I started truck and it died which appeared to be fuel issue. Both tanks are full but I hit the other tank switch anyway. I then noticed fuel rapidly running out a hose in engine bay. This is a first so I put a Vice grip on it to make it stop. After a little investigation, it appears the gas is coming from the unused non plugged return line. I then confirmed gas at the carb and it starts and runs normal.

Is the selector valve failing? Maybe a grain of dirt keeping a valve open? I run the red pump because I have a vortec block without a fuel pump rod. I would prefer to use in tank pumps if they are still installed. One of the two sides fuel gauge reads pass full too, not positive but after the spill it appears to be now working properly? How should I proceed? I looked for old threads with similar symptoms but didn’t find anything reviewing 8 pages. As always, thank you for sharing your knowledge and experience. I don’t drive it much but I have been working on restoration. I’m likely going to move the box for paint at some point.

 

[MarineOne]

Is your pump pre or post valve? Also efisystempro.com has a really nice modern selection valve

 

[mxer147]

Holley pump located on the inside frame rail under passenger seat between the selector valve and engine. Thank you for the information. I couldn’t find the selector on the website, please provide part number?