Vehicle is a 1999 chevy silverado, 2wd, 1500 base model with a 4.8 VL engine. Mileage is 211,500. Oil change every 3 months. Fuel filter, gas pump, cabin filters are all brand new. The trouble I am having is when I turn the key over it takes longer for it to start. Before it would start right over, and now sometimes the lights dim just a little and it is fine. I had the alternator, Battery, something else tested, don't remember, but I know it checked out fine. The vehicle is making a noise under neath the front of the vehicle. I don't know what it is, the noise seems to exist when I press the gas, other than that if I press the gas and then let go it doesn't make the noise. Had got a word that it might be my vapor pressure sensor not giving enough gas for the vehicle to start. : I do would like this resolved so I have some idea where to begin, because I do need my vehicle to commute to work each day. Thanks for your time.
As far as the hard starting. I would guess it is the fuel pressure regulator. It is located on the fuel rail(vacuum pot). There is a line that goes to intake vacuum, pull the line off the reg right after you shut it off, If there is fuel then its bad. The buzzing noise could be the electric A.I.R pump running.