So i got an 88 Firebird with a 5.3/4l60e. At a cold start it starts up right away and no issues. After it warms up and shut it down and turn it right back up also starts right away with no issues. The problem is letting it sit for maybe a half an hour is when im getting these long cranks. I hear the fuel pump prime up the lines but it cranks for about 3-4 seconds as if theres no fuel reaching it. I have replaced the fuel filter/regulator and fuel pump. Spark plugs and wires are new. Injectors are new. I cant figure this out at all. Any help is really appreciated.

 

Check for kinks in the line. Visually look through them. You can always put a fuel gauge on the line or right before the rail to aid in trouble shooting. It may be something else too. Do u have ur MAF in front of your TB so there’s air going by it?

 

Probably needs some tuning to fix.