I've written several posts on these heaters (especially the chinese models) and how they are prone to failures and the buyer/owner really needs to keep a few spare parts handy...especially a couple of spare fuel filters. This might be the problem with yours.
Usually when these quit it's at 3AM and -10 degrees and 75 miles from nowhere. I ALWAYS recommend a back-up heat source, even if that backup is your vehicle engine. You have that issue covered.
In the trucking industry we call them 'bunk heaters'...not 'diesel heaters'....so when you contact a truck repair shop, use the term 'Espar bunk heater'...if you call it a 'diesel heater' that person may not know what the heck you are talking about.
In the trucking industry a 'diesel heater' is a fuel heater that does exactly what it sounds like...it heats diesel before it enters the engine's fuel injectors.
BTW is this a diesel engine van or a gas engine van with a separate diesel tank for your bunk heater?
Reason I ask is your statement, 'back on the road' causes me to wonder...if that heater is pulling old fuel from a small diesel can or tank or bottle that only feeds the heater, and not the engine, it could have gone bad or gelled and/or absorbed water and you may get lucky just putting in a new fuel filter.
Or it could be the metering pump or the ignitor module. Hard to know for sure until you get someone to look at it.
