My 90 300 six fires up then imediatly dies, the next day starts and drives like new. I can hear the feul pump prime, any ideas?

 

Have you checked fuel pressure? Have you checked the fuel filter? Does the fuel pumps sound loud?

 

I haven't checked feul pressure yet but pump sounds normal

 

I had a 90 f150 with a 300 straight six. Would start and idle, but when you tried to rev it up. it struggled. Replaced the fuel pump, problem solved. FYI I didn't buy the godly expensive fuel pump for this truck. I bought a cheap fuel pump for a 90 mustang GT. Then i took apart the plastic unit inside the f150. And inside this "contraption" was the same fuel pump as the mustang. Just replaced it and put the plastic unit back together, and worked perfectly.