I have a 2006 f250 powerstroke that dosent want to start. the engine turns over and fires but dies out. the problem is gtting progesevely worse. the truck will start after a while and will start the rest of the day but come morning, good luck. i dont think it is the glow plugs because iv plugged in the block heater and same results... im late for work. any help would be greatly apprecited.

 

It still could be the glow plug's or the glow plug relay, the block heater just keeps the coolant temp around 100 degree's i do believe and does help it start easier but the glow plug's heat the in coming air too a certain temp too help start
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Sounds like its the Glow Plug Relay under the hood, its in the box on the drivers side closest to the cab, its big and gray, should be about $15 at the dealer. Thats where I would start. Does the Glow plug light go out when you leave the key on for a minute first thing in the am?