My 2004 f250 after it sits it wont start. the wait to start light only comes on for bout1 to 2 sec. the only way i start it is to plug it up at night what is my problem.

The wait to start light always comes on for at least 1 sec, if it goes off early it must think the engine is warm.

My guess is you have a faulty engine oil temp sensor that is telling the pcm that it is already warm. The only way to know for sure is to read the info with a scan tool.

Glow Plug System: Description and Operation
GLOW PLUG SYSTEM
The 6.0L diesel engine uses a glow plug system that preheats air in the combustion chamber to improve cold engine starting.
The system consists of:
- glow plugs.
- glow plug control module.
- powertrain control module (PCM).
- engine oil temperature (EOT) sensor.
- barometric pressure sensor (BARO sensor).
The glow plug monitor system is part of the On-Board Diagnostics II (OBD II) System.
The glow plug system is electronically controlled by the powertrain control module. If the oil temperature is below 55°C (131°F) the powertrain
control module will energize the glow plugs immediately after the key is placed in the ON position. Then, depending on the readings from the engine
oil temperature (EOT) sensor and the barometric pressure (BARO) sensor, the powertrain control module determines how long the glow plugs will be
on.
The glow plugs are located in the cylinder heads, under the glow plug buss bar.
The glow plugs are self-regulating. If the engine oil temperature is above 55°C (131°F), the powertrain control module will bulb-check the WAIT TO
START lamp but not energize the glow plug relay.
The glow plug ON time varies from 0-120 seconds depending on battery voltage, engine oil temperature and barometric pressure.
The glow plug control monitor (GPCM) system is designed to find failed glow plugs or failed wiring in the glow plug system.