Electric pump before or after mechanical

Problem stems from modern gas. Old fuel had stabilizers in it because everyone had a vented fuel system. Now cars have a sealed system and fuel injection. I was first made aware of this by Herb Macandless (sp?) at a clinic at Carlisle. Per his instructions a small impeller electric pump that the mechanical fuel pump can pull through is the ticket. I only use the electric pump to prime the carb and then turn it off. Has worked great on 2 street cars for 5 years now.