I drove my truck this morning and it was running great. Drove for about and hour and i Had to get some gas so I turned it off pump my gas and went to start it up again. It slowly cranked over for a few revolutions and then nothing. Smelled something burning so i Opened the hood and noticed that the ground cable that runs to the engine had heated up to point it started to melt the insulation. Also saw some smoke coming from the starter. The starters only 3 months old and the battery, battery terminals and alternator are all new too.

 

Everything may be new except you neglected the battery cables. You either have a bad cable or a bad connection. This cause a lot of heat and the cable overheats melting the insulation.It also overheats the starter. Check the battery cables at both ends not just at the battery.

 

Cleaned terminals and replaced all negative cables it starts but when the truck is warm it still turns over really hard