I'd recommend you do a battery test and charging system test. The battery would be my first suspect.
The starter or battery could be weak. The weakness will cause the starter to turn too slowly to start the truck.
Sounds like a starter issue. Bad wire to the starter could cause it.
Remove and replace the starter.
the solenoid is bad on the starter. soon after this problem starts tapping on the starter will not work either any further questions email me at crazyarmydad@hotmial.com
The starter solenoid is bad.
on top of the starter
The starter for a 2002 GMC truck is located on the passenger side of the block by the transmission.
Could be a shorted wire, or bad battery.
There is no such thing as a 310 Chevy truck.
There is only one starter per truck. If you follow the positive battery cable from the battery it will lead to the starter.
starter solenoid is connected to top of starter
you disconnect neg. side of battrey and then raise the truck and some times over the th rt front over the tire you can get to the wires to disconnect if not go under car and look at starter should be able to acess the wires only 2 of them then take the 2 mounting bolts for starter, remove them and then sneak the starter out it will be alittle tight to do so take your time. there might be a shim between starter and engine if so must use it with new starter unless the new starter may say no shim needed, would be printed on the head of starter. if no shim install with no shim. when installing and you connecting wires be sure that wires are not! touching together if not sure when you go to connect battery it will spark badleyand starter will engauge at that point leave battery disconneted double check wires at starter.