Hard starting diesel engine when engine is hot?

Most of the time a diesel has a hard time starting when its cool. When they have a hard time starting when hot, it is usually caused by the fuel running back into the tank. Check for a cracked fuel filter housing or a cracked low pressure fuel line. It is possible you have the wrong fuel filter. Install a top quality name brand filter like Wiks or Baldwin that has an anti bleed back valve in the filter.