After repeating myself several times in threads sooner or later you all will listen. This new ethanol mix fuel will cause this issue with all carbureted cars.
The only way to get these cars running like they did back in the day is to add a return to prevent boiling fuel from letting the dead ended pressure from seeping past the needle and seat. This is due to the float dropping from bubbling fuel the float sinks because air bubbles don't lift the float.
After installing the filter on many cars I found you can reach in the window and tap the key to restart the car when warmed up. Air fuel ratio stays consistent while running in all temperatures and driving conditions . Most cars have a problem without the return and seem to flood and a part throttle is needed to restart.
Different carbs will act different due to float composition. Hollow brass floats are worse then the plastic style. I must have done 100 of these returns since the 80's . All the carbureted trucks and cars before fuel injection in 1988 came with a return filter for this reason. I thought many of you would know this. Evidently not. Good luck.
Every car built here gets a return filter. unless its an electric pump. Then they get a bypass regulator with a return, To make it easy to run the return line on a manual pump car buy a fuel vapor line from 71 to 76 it runs along side the fuel line.. That is what I use for the return line.
We just did this 67 Barracuda to correct this problem . We used 71 lines and a fuel sender with a build in return nipple. That is why they sell them. 72-76 tank the nipple is already in the tank above the sender.
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