You rebuilt this starter? Check the brush system and your lug contact inside.
I do see many Delco starter rebuild kits with only two field coil windings. Some are for 12V conversion. Some for tractors. If you have installed a 12V conversion kit and running off of 6V. Could be a problem.
You need to take the warning from Kevin. The battery! Try a different battery.
Make sure the coil on the GMC motor is not wired for positive ground. But I guess the bench test eliminates that.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn |