Irregular fuel pressure

more like fuel percolation with todays new fuels. If you can, run a bypass filter with a return to the fuel tank. Another idea is to use some fuel injection hose instead of hard line. it insulates much better. Also, the quality of standard over the counter fuel pumps is not that good. Of course, quality fuel pumps are way expensive. try to keep the heat away from the fuel line to the carb from the pump. Another problem with the cheap pumps is that the built in one way valves sometimes leakdown and cause hard starting.
Its all supply and demand- there is not a big demand for mechanical pumps these days so that effects the quality. Same thing goes for the alchohol in the gasoline- not at all good for a car with a carburetor but works just fine in a fuel injected application with tons of pressure and a big return to the tank to keep the percolation down.