I have a 98 Blazer 4X4 with the Vortec engine. I have replaced the fuel pump twice in less than 2 years. It would not start for me and took to a shop to have put on machine to check ignition. All seems good and they feel the pump is going again. They say it is losing it's prime. My question is how can an electric pump lose its prime? I suspect the fuel pressure regulator is leaking. If it is leaking could this be the cause of the pump losing its prime. They say once it is running the pressure is good, just that after it sits the pressure bleeds down. Unless someone has a better suggestion I'm thinking of replacing regulator first then look at the pump. Any help is much appreciated.

 

Test it. Follow the information in the 96+ Fuel System Diagnosis post. If you follow the steps in that thread, it should identify the faulty part for you.