All,

I have had a recurring (and intermittent) problem for about the past year, and no one seems to able to figure it out yet. I hope someone here might have a new suggestion.

Equpiment:
1999 Road King with the M-M EFI system. I have a PC IIIr module installed, but the issue wxisted before that.

Issue:
Typically, the problem starts about 200-300 miles into a trip. It dosn't seem to be affected by really hot (or cold) weather. When cruising at around 80ish, I will roll ontot the throttle to pass someone. At around 90% throttle, the bike will cough like it is out of gas. I'll back off of the throttle and try to pass again. If I do this for a little bit, the "lean" point moves further down the throttle position until I can barely keep my speed at 70ish. Pulling to the side and cycling the bike's power will make the problem go away. However once it starts, the problem will continue to recur every 20 miles or so. After the bike finally sits over night, it's fine...until around the first few hundred miles again.

I had a friend riding behind me when it was happening. He said he could smell a lot of fuel coming out of the exhaust, so the gas was getting in alright. I already replaced the engine temp sensor, and that wasn't it.

I am ready to pull out the whole system and throw a carb on the bike, but I am not convinced yet that it's the EFI system. But, I am getting desperate and don't know what to try. I'm trying to leave for Sturgis (from California) next month and don't know if the bike will make it this time. I can't reproduce this thing for anyone to get a dyno read on.

I'd appreciate any advice or similar stories to try and figure this thing out. Thank you everyone.

-- Matt

 

How many miles on it? Is it when the fuel level is low? Have you ever checked for the tank liner peeling and blocking the fuel pick up. Can you provide any more details about when it occurrs? Have you performed a fuel pressure test and also watched that it holds pressure after turning off power?

 

When you say "no one seems to able to figure it out yet", what have they tried? Has anyone replaced any parts while trying to troubleshoot the problem? And if so what parts?

 

Has the Crank Position Sensor been looked at?

 

My Evo did something like that, bit not as predictable or consistant. Turned out to be the coil.

 

Hi,
Sounds to me as though there is an ignition problem. In this case hot or cold weather riding would not be an issue as the coil will produce its own heat regardless, thus breaking down. I would look for any deformatity in the coil at the same time check the plug leads and caps. Check the primary connections to the coil also. Could be loosing spark intermitently, just for that second or so.
Could be other issues but this is a good start after reading your problem.
Let us know how you get on
Cheers

 

first thing I would check would be the connectors to the ECM. be sure they are clean and making a good contact. Once cleaned put some elect-grease on them. Next check your grounds and be sure they are clean and tight. I think this is more electrical than anything else.