Q&A

My truck stopped running like it went out of gas while i was driving. I determined it was the fuel pump and had it replaced. The truck ran fine for 4 days, I went to start it and it wouold crank but not turn over. I realized the fuel pump runs without the key in the ignition but shuts off the minute I try to start it. The pressure is 40lbs the relay is good on all relayts in the box, the connector to the fuel pump is a one way connect so no splicing errors on my part. Im at a loss and no one has seen this before Please help