1999 GMC K3500 Sierra SLE 8 Cyl 5.70L
Truck sometimes has a very hard time starting.
Truck has hard time starting sometimes. Truck will finally start after 20 minutes or more holding gas pedal to floor, compressing and decompressing. Fuel pump was replaced last year. It has this problem sometimes, when it doesn't do this it starts right up.
Try turning the key on and off for 3 seconds a few times before attempting to start. The pressure may not be holding at the fuel pump causing there to be no fuel available for starting especially after sitting for some time. There is no need to press the pedal or hold it down. The fuel pump will add fuel each time you turn the switch on and off, without trying to start the engine. About three or four turns of the switch first, then try to start the engine. I have one that used to take three turns on and off and now takes four after sitting overnight. Hope this helps.