Fuel pump went out and replaced it know car with turn on but barely run at 400rpm then die when i give it gas, i adjust the idle up and it wouldnt start. Im stuck and dont know what to do.

 

Its a 89 with 92 ls swap, it wont let me save my edit.....

 

Could be bad fuel pressure regulator, idle control valve, was it running beefore the swap after the swap? Could have intake leak there are endlis possibilities need more info.

 

The swap has been in for a couple years ran fine, till fuel pump went out one day. When it stop working i did take off the fuel rail to see if injectors were squirting. The fuel pump i put in was smaller in size, it came out of a 96 i think.

 

You have to check the pressure rating if it's to low it won't work

 

On the fuel pump?
I was kinda thinking that cause i looked on Oreillys website and it had 4 different pumps and all had different gph ratings.
What if i put a walbro 255 on, would i need a pressure regulator?

 

You need to find out what stock pressure fuel pump is made for your motor then go from there just get the stock presser no need to go up in pressure unless you want a high flow rail and injectors upgraded