Pumpkinray

Vacuum from the engine to the fuel pump, causes the diaphragm to pulsate in and out, pulling fuel from the gas tank and pushing it to the motor

Recently purchased an aftermarket fuel pump was defective, right out of the box would not pump any fuel. The old one worked fine. It was just leaking fuel. They sent me a replacement free only to find out that one didn’t work either after several hours of troubleshooting replacing fuel lines, checking fuel petcock only to discover that the small spring in the fuel pump was too tall, not allowing the diaphragm to pulsate the spring, measured 9/16 of an inch tall by placing it in a vice and shutting it down to half inch and reinstalling it back in the pump. it worked perfect this might help someone with the same issue in the future .