Hey Scotty love the channel. Need help I have an old 1991 GMC C1500 5.0L V8 truck. It won't start. I've had the ICM replaced the spark plugs replaced and the fuel filter and injectors too. It would run in between the parts being added but a day later it would go kaput. I just checked the injectors no fuel coming out with just a turn of the key or even cranking. Heard buzzing from fuel pump when looking at fuel filter with key turned. I can't figure out if it's the MAP Sensor or the fuel pump is starting or has gone bad? Can you help me?

pressure test the fuel pump to see if it's bad, and do this general video https://www.youtube.com/watch?v=064Ilsz8Fzg&t=56s