I went to bike week in Daytona... overall an excellent experience! Anyway, while on a ride my bike started running terribly after stopping for lunch, backfiring through the throttle body and pipes with no power.

To me, this means that the computer (Power Commander III USB or HD's) has electrical problems, the injectors went wacko, or the fuel is interrupted somehow as far as I can figure. I turned off the bike, checked for shorts under the seat, turned it back on with no improvement. Went down to a gas station, filled it up with gas, and it ran fine. So... I think... I've got a hole in the fuel line inside the gas tank. Everything goes fine for the remainder of the stay which had included some long rides prior to this long ride. On the way back, it happens again. I had stopped for lunch, take off riding, and it starts backfiring again. I turn it off, turn it back on, and it starts running ok for the remainder of the trip.

This happened once before about 6 months ago.

The amount of popping on decel has been increasing it seems and the bike surges when running on low rpms... below 35 around town. Not bad... just annoying.

Of course, the Harley Dealer in Palm Bay FL says it's the power commander and talks about how they blow up HD ECM's etc. I say this bike has run great for three years with the PCIII installed. Now, these things don't get 'out of adjustment'. I do intend to bypass the PCIII the next time it happens (my bike was loaded up and I didn't want to unload it when it happened last) but hey, if it runs after turning it off and back on, I wouldn't know if it was the PCIII or the fact that I just turned it off and back on.

Anybody ever hear of this kind of thing? I really don't want to keep riding it until it gets serious about whatever problem it has so that I can reproduce it so any help will be greatly appreciated.

C#

 

Fuel line inside tank. When it's full it'll run fine but when the gas gets below the hole in the fuel line from the fuel pump it'll run funny. Replace the fuel line inside the tank and it'll fix it. I had the same problem for a bit.

 

So, how big a deal is that? Also, the bike will run some times it seems with the fuel below the 'problem' level. Actually, the bike ran bad after taking a hard corner when leaving lunch at 75 miles. The next time it was 73 miles. Other times I made it through 4/5 of a tank. I haven't looked at the manual to see if I think that the fuel line 'floats' in the tank. It can't help to eliminate the possibility...

Thanks for your help.

C#

 

Simple test. Do a normal startup and then shut it off. Pull the fuel pump fuse. Wait one minute.It should start and run a few seconds with the fuse out. If not you have a hole in the line bleeding off the pump pressure or similar problem. Could be a plugged filter also depending on miles.
This check will likely throw a code, so just clear it and it won't return. If you have availabilty of a fuel pressure tester it would be the best check, as it will show pressure and any leak down problems at the same time. Personally I don't think this is your problem, but at least you can rule it out.
Ron

 

Great tip. I hope I don't need to use it, but that's why this site is SO great..... people like yourself. I'd like to see a pic of your bike. It sounds great...... JR

 

Thanks! I picked that up elsewhere on the internet yesterday but it certainly is a good tip. I am glad that we all help each other out on this forum since HD won't issue these kinds of notices and tips to their owners... this IS a design defect if it's happening so much that people notice.

C#

 

heard of that before, called bad gas, maybe some moron pee in your gas tank

 

Well, it passed the fuel pump test so there isn't a hole in the fuel line.

Unless I got bad gas twice in the same trip from reputable companies, I don't think it was that and no one put anything in the tank because it wasn't somewhere that it was possible to do so.

I guess I will wait until it breaks down again and bypass the PCIII.

C#

 

I sometime get that.....after pizza and beer! (Sorry, couldn't resist)

 

It sounds like it may be a LEAN fuel condition. It could be possible that the PCIII is the problem. You could always ck the "map" to see if it has changed in any way especially in the lower rpm area.
Fuel pressure being low as stated earlier could do this also.
Another thing it could be is a plugged or restricted gas tank vent hose. If it does it again, loosen the gas cap and see if it gets better. If it does, I would look at the vent hose or vapor tank.
It could also be a intake vacuum leak. At idle you could spray something like WD40 around the intake area where it meets the heads etc.. and see if the rpm,s change (I would suggest a cool motor for this).

One other thing I saw was on my friends Fat Boy was a loose spark plug wire believe it or not.

Just some of my thoughts. Hope it helps and your cure is something simple.