Ginpole- is it not turning over enough so as that it won’t start?
My gmc is still 6v/positive ground and they do turn slowly, when compared to any 12v vehicle.
***If it turns over slowly and is right on the edge of starting or not starting, a good tip I learned is to press the starter button first and then once it’s rolling over turn on the ignition switch. That lets it turn without the back pressure of it trying to ignite until it’s rolling and ready.