My duramax wont start when its below 20 degrees,glow plugs were checked and said to be ok, put fass fuel on it to help fuel pressure,I have 345000 on it and want to at least get to 500000 miles.
It should fire without the glow plugs. Check to make sure you have voltage to the glow plugs themselves when they are on. Could be a relay. Also check to make sure you have fuel pressure when cranking.
I had Chevrolet do a full check and they said there were no issues,I thought the Fass Fuel would keep the pressure up,should I delete the stock filter.