I have 90 f250 replaced engine with block from 95. at first fuel pumps kept running whether the key was on or not just as long as battery was hooked up.
fixed that problem with new relay. now fuel pump shuts off with key. but with key on fuel pump does not shut off. wont start unless i spray starting fluid in intake then it starts and stays running. then it will start on its own . until after it sits for some time.
any ideas would be appreciated
thanks mike

 

The truck will not start up on its own? Do you have fuel pressure the first time you try to start it?

 

thanks for replying. ya when i turn key on fuel pressure goes right to 40 psi

 

thanks for your input Worf it ended up being the ecm