I have a 99 blazer 4.3 Fuel pump was replaced and the truck started. Now it won't start. I have plenty of fuel pressure, spark and all the relays seem ok. Any ideas of what it could be?

 

What is the fuel pressure in psi and does the pressure remain above 50psi for 10 minutes after the pump shuts off?

 

Fuel pressure stays up. I read some other threads that mention checking the battery. The battery cranks fine and charges fine but when I tested it the tester said the battery should be replaced. It seems to have worked although I don't know why it did because I don't know what the battery would have to do with it after the truck started.