Coolant is disappearing from the reservoir immediately as I fill it, No visible leaks from the truck anywhere. I'm not seeing milky oil when checking it so i don't believe it's a head gasket issue, I have no idea where my coolant is going. When i start the truck it sits on cold on the temp gauge for a good few minutes without moving then quickly shoots to overheating.

2002 Dodge Ram 1500, 4.7 L Magnum, after a use, it won´t start again, it cranks like is out of fuel, but after waiting 10 or so minutes,it starts and works like nothing is wrong. I changed the fuel pump and worked normaly for about 6 months and then,the failure it´s back. Note: Some times the engine temperature gauge goes a little farther than the middle mark but engine works fine. It doesn¨t show any engine code besides one oxygen sensor failure.