Need Help With a 4.3 Motor

My dad has been working on this Blazer for a while (1996 with a 4.3). Every time you turn around it's something. Here's the latest problem:

"sounds like its out of time. took off timing cover and its not out of time. it was running low or out of fuel when it quit. had no fuel pressure. removed filter and it was nearly plugged. i replaced the filter. still no start but i now have fuel pressure. it still sounds like its out if time and its not the starter or battery or cables. it has had a code po300 off and on and most recently code po440."


Anyone have any help or have you heard of this problem before? Thanks!

im gonna put money on your fuel pump... my dually and my other astro both had the same sounding problem. buddy of mine said it was the pump i said no did every thing else i could think of and it still wasn't right i changed the fuel pump ran perfect... pain in the ass.....

p0300 is an engine misfire and p0440 is evap emission system. fuel pumps are common. could also be injectors causing the misfire. i believe these have updated injectors.