Hello I am an Espar tech from Vancouver Canada. If the fan runs for three min. and then the heater stops, it is going through the start cycle properly(3 min. is the failed start timeout). As you said, number one would be to check the electrical connections for the fuel pump at the heater, and at the fuel pump.If they are ok then it is either that the fuel pump is stuck(it is a solenoid), or the control unit relay for the fuel pump is not closing and sending the pulsed 12v to the fuel pump. If your thermostat clicks and the grees light goes on when you turn it up, the fuel pump should start at the 25 second mark. If the thermostat always has both red and green light on when turned on then it has a different control box that turns the pump on at 60 seconds after turn on. When you find that the fuel pump is not working give it a good smack whith a screwdriver handle. If it now runs it was stuck. If so it may stick again and the fuel pump will have to be replaced($200-$250.00). part # 25 1482 47 00 00
You can also put a test light on the two wires going to the fuel pump with all wires attached. Turn on the heater and wait for the test light to start flashing. If it does not start flashing at either 25 sec. or 60 sec. then the problem is with the control box. It would have to be replaced($5-600.00) part number is on the box starting with either 20 1607 or 25 1688
If the numbers on your control box(silver box, near the heater) are 20 1607... then the fuel pump will start at 25 sec. If the numbers are 25 1688... then the pump will start at 60 sec.
If you need more help, you can call Roton where I work at 1-800-688-2325 My hours are Tues to Fri. 9-5 and Sat. 10-4. During the week I may be out on service call, but on Sat. I am in the store all day.
I hope this helps.