Hello, l have a 1996 chevy cheyanne 1500 truck.The motor is a 6.5L diesel.It starts and runs fine when l use throttle when starting, but when l dont this happens: http://s43.photobucket.com/albums/e368/JQA3/?action=view¤t=MOV-0001_1.flv .There is NO throttle used in the video.What could this be?Thanks
Replaced the oil sensor twice.

l am going to say oil pressure sensor in the back of the pump

l am assuming that this is the first start of the day & the temperature is colder.

It acts like it is cold. You more than likely have a couple of glow plugs that r not working well (or at all). l would bet that if u cycled the glow plugs twice it would start easier: Turn key to 'ON' position & after glow plug cycle completes, turn key off then on again. After 2nd cycle start truck. l am betting that the truck starts fine when warm?

You can check the glow plugs by doing a resistance test on each plug with a multimeter. All plugs should have a similar resistance, an open or infinite reading indicates a bad plug.

Plugging the block heater in will assist u with cold weather starts.

l am sorry l do not know what ur video is actually showing anyone.The wait light on the dash is for the glow plugs. l am going to guess that u never owned a GM diesel before.On the 6.5 ltr. diesel there is a high idle solenoid.The solenoid is not strong enough to push the throttle up.You have to treat it like if it had a carb.When u first turn the key on to light the glow plugs,push on the throttle about half way down or more & let it up.When the glow plug light goes out(its on a timer)crank the engine.It should fire up & hold a decent idle.Now the glow plug light will cycle on & off a few times after the engine has started.