My '02 Fatboy starting running rough and on idle engine quit. It would start back up but felt like it was running on one cylinder. Removed the plugs and the rear was black with carbon build up. Front plug was fine. Air Filter was very dirty. Installed new plug and kept filter off and started up and engine still felt like it was running on 1 cylinder. Pulled rear plug and it those few secs of running carbon was starting to build up. I had spark and wires with volt meter and wires were fine. It has all the symptoms of fuel injection issue but pulled the injectors, tested with volt meter and both between 15.8-16.1 ohms. Cleaned injectors and did not notice any issues with the flow on both injections so I don't think that was the issue. Was thinking it might be a dirty fuel filter but I suspect both plugs would read the same, not just the rear. Any suggestions before I pull the fuel pump and filter?

 

Swap injectors.

 

Did you clean the rear plug or replace it?....I never clean plugs on Harleys, just replace because once fouled they never come right again.