I recently had mysterious conkouts with my Coupe DeVille. Went though the basics and came up with nothing. Fuel filter wasn't clogged but it looked like I wasn't getting fuel to the carb even with a fully rebuilt and tested fuel pump.
Car started and ran great but could conk out after 20 minutes, 20 miles, who knows> Sometimes I could get it started sometimes not.
Anyway, the only thing I could come up with that was causing the problem was a blockage somewhere between the tank and the pump. I replaced the tank and the entire steel fuel line from the tank to the fuel pump - about 20 feet of steel line.
Haven't had any problems or hint of problems in the 500 miles I've driven it since the repair.
I found no smoking gun but the tank and line were original 68 year old items. Rust? Piece of gunk wedged somewhere in the 20" pickup tube inside the tank? Something in the 20 feet of line? Who knows? Don't take anything for granted even if it "looks clean" or you can blow air through the lines.
There was no visible rust in my tank but something wasn't right.
