So I have a 2015 Newmar Essex with a Onan 12,500 diesel generator. It starts easy but runs very rough similar to gas engine with the choke partially closed. There also is a lot of smoke coming out of the exhaust and leaves a black residue on the ground under the tail pipe. History, I bought the Coach used and it was running rough when I purchased it in 2020, I have no history regarding the previous owner or the coach but it was very clean when I looked at it prior to purchase. What I have done so for is to replace the air filter and check to be sure the intake system was clear of obstructions, oil and oil filter change twice, new belts, three new injector nozzles, and cleaned the radiator (also I have replaced the fuel filter twice). It is putting out the correct voltage but under hard load in high altitude it will not pull the load on my last trip. In lower altitudes it is fine as for as pulling the AC’s and such but still runs very rough. I have discussed with others and with a Cummins Onan technician and a couple mechanic that did not really have an answer. Cummins suggested bringing it in and let them put a hard load on it for a couple of hours. This is my second coach with the same generator and my previous generator ran very smooth.
Has anyone ran into this with their generator?
Has anyone ran into this with their generator?