The fricking ignition saga continues...
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Cruiser
Joined: Aug 2012
Posts: 106
Likes: 0
The fricking ignition saga continues...
From August to now... after a long trip from Boston to Augusta, GA, my 1989 FLHS started giving me fits with the ignition, and did weird things like hiccup 200rpm if I operated the turn signals, headlight or driving lights.
I decided after troubleshooting to change the voltage regulator, which fixed the issue with the changes in electrical load causing hiccups, but one issue now remains.
When bike is cold, starts and idles great at 1000 RPM (btw, I had a new S&S Super E carb kit professionally installed). Let it sit for 10 minutes idling, no problem. But when it gets warm, RPM suddenly drops to 500 and it runs a bit rough. If I rev it past 1500 the issue goes away. If I drive it that way, it runs rough, backfires once in a long while, and all of a sudden will pick up and start running fine while on the road, only to do it again once I slow down and RPM drops below 1500.
WTF???? Charging system is fine. Voltage regulator is new. All connectors are good to go, free of corrosion. Ignition module? Ignition coil?
I decided after troubleshooting to change the voltage regulator, which fixed the issue with the changes in electrical load causing hiccups, but one issue now remains.
When bike is cold, starts and idles great at 1000 RPM (btw, I had a new S&S Super E carb kit professionally installed). Let it sit for 10 minutes idling, no problem. But when it gets warm, RPM suddenly drops to 500 and it runs a bit rough. If I rev it past 1500 the issue goes away. If I drive it that way, it runs rough, backfires once in a long while, and all of a sudden will pick up and start running fine while on the road, only to do it again once I slow down and RPM drops below 1500.
WTF???? Charging system is fine. Voltage regulator is new. All connectors are good to go, free of corrosion. Ignition module? Ignition coil?
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
My vote is the ignition sender unit! I had recurring mystery problems for a couple of years that were a bit of bother to start with, then left me stranded in the central reservation of a busy rush-hour motorway. The engine would still run, but not take any load to move.
Road Warrior
Joined: Dec 2007
Posts: 1,666
Likes: 3
From: Styxville
Have you tried a new battery?
Sounds trite I know. But I recently bought a 95 Road King with the worst case of cold starting carb farting and missing and carrying on I've ever seen. I figured for sure the carb was clogged with junk or the jets too small etc etc.
But it was cranking over a bit slow, so I put in a new battery and all the bad running hot or cold disappeared. I think the electronic ignition on these things is sensitive to low battery voltage maybe.
Sounds trite I know. But I recently bought a 95 Road King with the worst case of cold starting carb farting and missing and carrying on I've ever seen. I figured for sure the carb was clogged with junk or the jets too small etc etc.
But it was cranking over a bit slow, so I put in a new battery and all the bad running hot or cold disappeared. I think the electronic ignition on these things is sensitive to low battery voltage maybe.
Road Master
Joined: Jan 2008
Posts: 1,187
Likes: 8
From: Montgomery, AL
Have you tried to pull the cover off the nose cone and look at the ignition plate? I went through this with my Fatboy. The glue was all melted. It would run good 75% of the time and then would act up. Spitting out the carb etc. Is it the factory ignition sensor? Also verify all of your grounds are good and clean.
Club Member
Joined: Apr 2011
Posts: 5,817
Likes: 7,849
From: SE Louisiana
When the idle drops to 500 after warm, disconnect the wire(violet?) for the VOES and ground it, see if idle returns to normal.
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Cruiser
Joined: Aug 2012
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Have you tried a new battery?
Sounds trite I know. But I recently bought a 95 Road King with the worst case of cold starting carb farting and missing and carrying on I've ever seen. I figured for sure the carb was clogged with junk or the jets too small etc etc.
But it was cranking over a bit slow, so I put in a new battery and all the bad running hot or cold disappeared. I think the electronic ignition on these things is sensitive to low battery voltage maybe.
Sounds trite I know. But I recently bought a 95 Road King with the worst case of cold starting carb farting and missing and carrying on I've ever seen. I figured for sure the carb was clogged with junk or the jets too small etc etc.
But it was cranking over a bit slow, so I put in a new battery and all the bad running hot or cold disappeared. I think the electronic ignition on these things is sensitive to low battery voltage maybe.
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Thread Starter
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Cruiser
Joined: Aug 2012
Posts: 106
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I'm taking to a shop in Jamaica Plain (MA) and have them look at all this. I've been wondering about that and the engine crank speed sensor...
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
it could end up bing the ground under the bike as it is rubber mounted, they have a special ground connecting the chassis to the motor - when it comes loose and looses it conection sometimes --- Hot Verces cold -- you can have some of the issues you are having ---
it conects the frames cross brace under the trans to the inner primary on the back side - in the same location, the ground strap is only 8 inches long and its woven not a plastic covered cable-- johnjzjz
it conects the frames cross brace under the trans to the inner primary on the back side - in the same location, the ground strap is only 8 inches long and its woven not a plastic covered cable-- johnjzjz
Last edited by johnjzjz; Oct 11, 2013 at 06:16 PM.