Fellas and Fellettes.....new to the forum but have been riding forever. My current ride is finally causing some problems...need a little friendly advice. Bought my '02 Road King Classic (fuely) new in '02. Standard Stage 1 mods....SE air cleaner, V+H slip-ons, and HD Stage 1 fuel map. I've got ~33K miles on the clock now but haven't ridden much for the past couple years. Active military duties have called me away far too often. When stored, I put Stabil in the tank. When I get back, run it dry and refill with fresh fuel and a little Seafoam. Seems to have worked well for the past nine years. Anyway, the bike has been very reliable and rock solid all this time until recently.

Symptoms...stammers and stumbles (coughs) under partial throttle periodically. Not all the time. Sometimes it'll go 40+ miles without a cough, sometimes not. The best description I can give is that it starts to cough like a carb'd bike does when you need to switch over to reserve....seems fuel starved. Being a fuely with a full tank of gas, obviously that isn't the case. Fuel pump is fine, pulled it and replaced the filter and line last spring at 30K. Pressures up and shuts down as it's supposed to. New battery a month or so ago....ouch...$185! Does NOT pop any codes or CEL so it's probably not electronic or an actual misfire condition. The only pattern I can seem to distinguish is that it runs rougher and coughs more frequently when it's hot outside. For example, this time of year it's cool here in the mornings (around 50*F) but has been warming up pretty good by the afternoon (~75*F yesterday). The bike ran like a raped ape on the 45 mile trip to work in the morning. On the way home, after about the first five miles it started coughing periodocally.....got worse the more I rode, even died at a stoplight for the first time ever. It doesn't backfire, only normal popping on deceleration but it has popped through the intake a couple times. Again, coughing seems to only happen at partial throttle....rip it open and it goes.

My gut tells me it's an intake leak. Possibly a partially fouled injector or leaking injector seal. Did the WD40 leak test (nothing unusual noted), pulled the plugs...both look equally like a hot/lean mixture....light grey/white but no nasty deposits, damage, glazing, oil, or blistering.....super clean. Don't have the money to bring it to the dealer for $200 worth of "troubleshooting time" to end up telling me it's fine....again. Besides, I'm a firm believer in doing your own wrenching....I trust myself (and the manual) for most repairs and maintenance far more than the average guy might but, admittedly, I might be stuck on this one.

So, I throw myself at your collective wisdom. Thoughts, ideas, or solutions?

Thanks in advance for the advice.

 

My two cents would be to clean the carb real good, was gonna say plugs also or possibly bad gas, but you mentioned that. That's where I would start.

 

Some ideas:

The corrugated pipe inside the tank that runs from the regulator to the external fitting is known to rub against the tank and form tiny holes in it.

The check valve in the quick release fitting could be partially blocked with sediment (bike stands for extended periods)

The external fuel line from the quick release fitting to the fuel injectors can fail internally, causing random partial blockage of fuel to the injectors.

The injectors themselves could be partially blocked or leaking.

In some cases (I'm not sure if it applies to '02 tourers) I remember that the wiring harness to the injectors is fractionally short causing poor contact to the injector and subsequent misfiring. I think that in this case a code would be thrown however.

Last idea - i have seen the decorative cylinder head bolt covers causing the spark plug to arc against them producing a misfire.

 

All good ideas, thank you.

When I tear it apart, the throttle body and intake will get a very thorough cleaning and gaskets replaced.

Replaced the corrugated pipe last year when I did the filter at 30K. That issue is usually easy to diagnose by hearing fuel spray inside the tank for a pin hole or the pump not shutting down if it's a larger hole (not pressurized) as the fuel level drops below the hole. Mine does it anywhere from empty to full....no spray sound and the pump shuts down as it's supposed to.

Already cleaned the check valve and quick disconnect....clean as a whistle.

External fuel line.....yup, possible. That would lead to injectors being partially blocked. Makes sense, will investigate.

Will check the injector harness just to be sure but, yeah, both that and a plug arc should throw a DTC. No DTCs for me yet.

Thanks again. I've been head scratching on this one for a while. At this point, any idea is a good idea....keep 'em coming.

 

My '02 Road King Classic did something similar. It ended up being the rear injector harness was cooked and brittle. Would create a "open" at times. But mine would turn on the check engine light (actually it would flicker off and on when it was happening).

Good luck, keep up posted!

 

My guess with the history you quoted is a partially blocked injector. At partial throttle the gas input is "low" so it is a bit more susceptible to problems than at high throttle openings. Depending on where you live, I understand some premium gas may have ethanol in it. Based on another forum I understand that staybil may not always work as well as it should with resulting gas separation and blockages. Solution seems to make sure your premium has NO ethanol in it.

 

Theakerr....partial blocked injector is on my list of possibilities. I seriously haven't had time in the last couple weeks to tear into it but will this week. I'm gonna start simple and go from there....take the intake apart and give it a solid cleaning. If that doesn't work then I'll start throwing parts at it until fixed. Will repost with the solution when I find it.

Frontier....yeah, no codes on mine so probably not electrical. It makes sense with the short you mentioned that it would pop a code.