66 289 c code fuel pump problem...
Glad that she is running well.
It would help[ if we knew what type of connections
you have to the fuel pump.
I assume a metal line coming out fo the pump to feed up to the carb
I will also assume - - a metal line feeding to the pump.
It is possible that you have a rubber hose at either end that a previous owner installed.
My thinking is that in either case the fitting is not right on the pump.
It could be crossed threaded or perhaps the wrong fitting.
I would determine if it is inlet or outlet and then
remove the line/hose nad see how the fitting looks.
Are these the lines/fittings from the OLD pump?
I am thinking you replaced the pump BUT not sure if that is the case.
It sounds like the fitting is messed up or NOT seating correct.