Yeah I have a 2003 blazer and I just replaced the fuel pump in it just the pump not the whole assembly the sensor on the top was broken I was told it was just to check the air in the tank and the guy that rebuilt it took a thin black hose out of it I think it connected to the valves on the bottom of the pump he said it was not needed also but anyway we started it up well tried and it took about 15 seconds for it to finally fire up n it ran a little rough but then it smoothed out i'm not sure why this is because it wasn't running like that before the pump we got was from advanced auto and after giving me the wrong one they finally gave me the right one. The fuel pressure gauge is only reading 30 pounds of pressure please help if you have an idea of what my problem could be?? Thank you

 

only 30 psi? you need 60 psi or more with key on engine off and when you turn the key off should not drop more than 2 psi, sounds like the pump replacement is defective, I would go with a quality OE replacement ac delco pump... sure they are a bit more expensive but how many times do you want to drop the tank and replace the pump?