Miller 251 NT will stick weld great for about 10 or 15 minutes and then the engine will begin to misfire and won't idle down and then doesn't want to strike an arc. Any suggestions. I had a tech look at it and he replaced the electronic box controlling the idle solenoid and a capacitor on the ignition coil, it worked well for about 6 hours and started doing the same thing again
Welding Tools - Miller
Answers & Comments
This is a very complicated machine and so I will say upfront that only a qualified tech should work on it. There are 2 fuses mounted on a tray holding PCB2. The tray is mounted on the lifting bail. The fuses need to be checked. Also there are circuit breakers and fuses mounted on the front panel that need to be checked. PCB2 is a control board monitoring the output and shuts down the weld power and aux power if there is an overload. The idle board is also watching the output and won't let the machine idle down if there is an overload. I have included the manual. Check Page 27 for overload protection and F1 and F2. An overload will occur if there is a shorted generator, shorted cube rectifiers, or shorted output diodes. Again, after checking F1 and F2, only a qualified tech should work on the machine. Good luc https://www.millerwelds.com/files/owners-manuals/O486H_MIL.pdf