72-350cid While shopping for fuel pump i see there are for AC cars and NO AC. AC has a return line. Why? Cheers!
A/C cars run hotter than cars without A/C. From the compressor load and the heat from the condenser in front of the radiator. Heat makes vapor lock more likely. The return line returns hot fuel and vapor to the fuel tank. It keeps fuel in the pump cooler fighting vapor lock.