I'm fairly new to this Harley game so bear with me as I try to learn.


I bought this bike a couple years ago from a friend of mine at work with 5500 miles on it and I've just gone over 8200. I've had no issues with it since the day I bought it, other than typical routine maintenance. I noticed this spring when riding into work that it missed and backfired a couple of times after the engine warms up. Since it has a V&H exhaust and FuelPak I figured it was running lean with the cool air, I e-mailed their tech and changed the map per their request. I filled up and rode about 100 miles over the following weekend and it was flawless, best it's ever ran. Then Monday I rode into work and about halfway there it started missing terribly under acceleration and even backfired a couple times at about 55mph. I got to work, shut it off, came back out at lunch and it took off perfect, about a mile into the ride it started to do the same thing. I changed spark plugs and the battery Friday (original battery) thinking maybe that was part of the problem, but it still developed a bad miss under acceleration once it warmed up. When I got home I ran it in the driveway and noticed it was blowing some black smoke when I revved it, telling me it's running rich.


The engine light has not come on, and there are no codes when I check them. Experience tells me any number of sensors that are not necessarily shorted out, but are reading incorrect range, can cause this but the most obvious are the ET, IAT, or 02 sensors. Any advice? I don't want to just throw parts at it for the hell of it.


Thank You

 

first thing I check is fuel pressure. make sure it's right. then go from there

 

To check the fuel pressure you just tap a gauge into the quick disconnect at bottom of the tank correct? I have a fuel pressure gauge for automotive use, does the Harley use a special kind of fitting to tap into it? I haven't taken it apart yet.

 

yes they have one u can buy