Not sure if this is the place to ask, but I've got a Dyna-Glo KFA650DGD 650,000 btu heater. It does not want to ignite by itself, but if you have the top cover un-screwed and you lift up the back end while its starting, it will ignite and run just fine. The obvious problem is when it doesn't ignite, it blows diesel in the shop and when you get it started, it smokes bad for about 10 seconds. What should I start with to remedy this problem?
Usually those are a "draw" type suction line from the tank to the burner nozzle. There is always a filter incorporated into the suction line. Change that filter, and the line that dips into the fuel tank both. The vacuum that draws the fuel is caused by an orifice in the back of the heater behind the air filter. Clean this with a soft tool such as a broom whisk or toothpick as most are plastic. These things work on inches of vacuum and any restrictions in the fuel supply render what you are experiencing. The fuel has to atomize and be blown by the blower onto the exposed electrodes in the burn chamber to ignite. Long and short is the heater needs routine maintenance performed.
When you're changing out the filter make sure to thoroughly clean the fungus and crud out of the tank too. These things are usually used twice then set for the rest of the year. Routine maintenance just like any other equipment. Once a year biocide gets added as well to make sure mine work when needed. Make sure to clean the flame sensor window while you're in there too, they get cruddy and affect the burn.
Just for my curiosity, why would lifting up the top cover allow it to ignite?
You are increasing the vorticity of the fluid medium, (diesel fuel) but significantly increasing the inefficiency of the heater unit. In layman's terms: The vacuum that is created to pull the fuel from the tank is increased.
After reading the manual for this unit, it appears that it has a fuel pump mounted to the back of the fan motor and it specifies a pressure of 110 psi which tells me it is not like the smaller units that use an air pump to draw the fuel from the tank. I would probably check the fuel pressure and go from there. Do you have the manual for the heater?
I do have the manual. I cleaned everything out, and adjusted the pressure. I have it set a little under 110psi. It gave out the least amount of smoke. It's still having the same issue, what else could cause this?
Is it possible that the heater has a "tip over" shut down? If it does, it may have become dislodged in the mount bracket and so the only way it lights is if you get it at the right angle?