Author Topic: 85 FLHTC misses under electric load  (Read 434 times)

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Offline jroestreich

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85 FLHTC misses under electric load
« on: May 24, 2018, 03:35:28 AM »
I have an 85 Electra Glide Classic that miss fires badly when I turn on anything more than the headlamp.  I have replaced just about everything.  New coil, plugs, wires, ignition switch (used couldn't find NOS anywhere), and the last effort was to replace the charging system.  With each step there was no change in the symptoms.  It runs great without any extra lighting turned on.  Should I be looking at wiring harnesses?  This one is a stumper.

Any suggestions would be appreciated.

Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #1 on: May 24, 2018, 04:21:06 AM »
I have an 85 Electra Glide Classic that miss fires badly when I turn on anything more than the headlamp.  I have replaced just about everything.  New coil, plugs, wires, ignition switch (used couldn't find NOS anywhere), and the last effort was to replace the charging system.  With each step there was no change in the symptoms.  It runs great without any extra lighting turned on.  Should I be looking at wiring harnesses?  This one is a stumper.

Any suggestions would be appreciated.
Ok a little test question for a one time poster to see if they are still reading, does the head light dim when you turn on the extra lights?

Offline Hossamania

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Re: 85 FLHTC misses under electric load
« Reply #2 on: May 24, 2018, 05:47:33 AM »
Have you replaced the battery? What is the running voltage at the battery, lights off, lights on one at a time? Have you checked for shorts in the harness at the neck, under the nacelle, under the seat? Have you tried unplugging the headlight and turning on the others?
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Offline Mark222

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Re: 85 FLHTC misses under electric load
« Reply #3 on: May 24, 2018, 03:46:41 PM »
Check ground cable attachment at battery post.

Had a misfire condition once on my '85 from something just that simple.

Might get lucky....

Mark

Offline Hossamania

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Re: 85 FLHTC misses under electric load
« Reply #4 on: May 24, 2018, 06:19:47 PM »
Check ground cable attachment at battery post.

Had a misfire condition once on my '85 from something just that simple.

Might get lucky....

Mark

Good point, start simple.
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Offline Flhfxd

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Re: 85 FLHTC misses under electric load
« Reply #5 on: May 25, 2018, 08:33:37 AM »
Broken battery ground wire? Seen this exact thing. The terminal was cracked and the bike ran like shyt
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Offline hogpipes1

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Re: 85 FLHTC misses under electric load
« Reply #6 on: May 26, 2018, 05:46:30 AM »
What's the volt meter doing when you turn on the extra's?  What are the extra's ?  Bike stock  lighting.?Did you R&R  the bad stock  ign. mod& pick up senser in the nose cone. ?  That  was my issue with my 85 FXRT. The turn on switch i would take a good look at also.

Throwing parts to fix it usually doesn't work. but new parts never hurt if you have the extra $$$ to put in it. asking here your on the right trk.

Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #7 on: May 26, 2018, 06:09:46 AM »
The op is a one post member and has not been on since he posted this question. That is why I ask the test question to see if he was coming back.

Offline kd

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Re: 85 FLHTC misses under electric load
« Reply #8 on: May 26, 2018, 07:11:11 AM »
Take a break fellas. Smoke em if you got em. This poster must actually be a poser. There are plenty of other needy folks asking questions that actually want to hear the answer or get some help. As said, he posted once and never came back to the site (in 2 days) to see if someone answered.
KD

Offline jroestreich

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Re: 85 FLHTC misses under electric load
« Reply #9 on: May 28, 2018, 03:55:04 PM »
Thanks for the replies all.  Sorry for the delay getting back.  I was looking for notification in emails that there were replies...my bad as the young uns say.  The voltage is hard at 13 volts with the new stator.  With the headlight only between 12 -13 closer to 13.  all this at idle.  Added lights it goes to 11-12 but misses very bad.  I rev to 2k or more and it smoothes out a bit and the volts go back up close to 13. 

I will look at the ground cable.  others have said it maybe ground in general.  I'll report back once I look at the cable.

Offline jroestreich

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Re: 85 FLHTC misses under electric load
« Reply #10 on: May 28, 2018, 04:08:16 PM »
Have you replaced the battery? What is the running voltage at the battery, lights off, lights on one at a time? Have you checked for shorts in the harness at the neck, under the nacelle, under the seat? Have you tried unplugging the headlight and turning on the others?

Great suggestions Hossamania.  I didn't think to unplug the headlamp.  That will let me check if the issue is total power draw or related to other circuits aside from the headlamp.  I will check and report.  Again, sorry for the delay.  New to the site and just learning the ropes.  Hope I didn't offend anyone.

Offline jroestreich

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Re: 85 FLHTC misses under electric load
« Reply #11 on: May 28, 2018, 04:19:44 PM »
I have an 85 Electra Glide Classic that miss fires badly when I turn on anything more than the headlamp.  I have replaced just about everything.  New coil, plugs, wires, ignition switch (used couldn't find NOS anywhere), and the last effort was to replace the charging system.  With each step there was no change in the symptoms.  It runs great without any extra lighting turned on.  Should I be looking at wiring harnesses?  This one is a stumper.

Any suggestions would be appreciated.
Ok a little test question for a one time poster to see if they are still reading, does the head light dim when you turn on the extra lights?


No.  It stays brite.

Offline Hossamania

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Re: 85 FLHTC misses under electric load
« Reply #12 on: May 28, 2018, 05:10:44 PM »
Don't worry, you didn't offend anyone. Pretty thick skinned crowd here.
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Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #13 on: May 28, 2018, 07:24:35 PM »
Are you checking voltage at the battery, what is it with the bike off? Have you started to check your wiring yet, have you pulled your connectors apart, cleaned the contact used dielectric grease in them?
I would say you have a voltage drop somewhere.
How are your extra lights wired up, are they factory?

Offline jroestreich

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Re: 85 FLHTC misses under electric load
« Reply #14 on: May 28, 2018, 07:43:08 PM »
I have some practical things to look at now from you guys.  Thanks.  I was hoping it was a simple part replacement but it appears it will be a contact, wire or ground.  Wire start the tedious task of tracing and testing.

headlamp and passing lamps are stock as well as the saddle bag lights.  I changed the turn signal and brake lights last year to LED but I was already having the issue.  Have not checked the voltage at the battery lately.  Had done it in the past.  Battery was new last season and has been kept on a tender.  Not having any problem with cranking so have not checked it assuming it was good still.  So my plan now is to start with the ground / neg battery cable the disconnect the headlamp and turn on the extra power to see what happens.  I can also look at the wiring.  will report back

Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #15 on: May 28, 2018, 07:56:54 PM »
Well your charging voltage is low, it should be at least 13.7 idle I would check it at your regulator.

Offline jroestreich

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Re: 85 FLHTC misses under electric load
« Reply #16 on: May 28, 2018, 07:59:21 PM »
Is there a test procedure to check the ignition switch?  I replaced it but with a used one.  I have not been able to find a new one in 3 years of looking off and on.

Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #17 on: May 28, 2018, 08:07:36 PM »
Is there a test procedure to check the ignition switch?  I replaced it but with a used one.  I have not been able to find a new one in 3 years of looking off and on.
Is it on the tank? Those you can pull apart clean to lube, to test you take a voltage read going in going out see if you have a drop. Same for your conectors, wires.

Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #18 on: May 28, 2018, 08:16:18 PM »
And you want to check them under load, (lights on)

Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #19 on: May 29, 2018, 04:12:42 AM »
Ok Iím on a regular computer so I can type. You said you have not checked voltage lately on the battery so I am assuming your readings are from the bike volt meter. We need to start checking with a good volt meter for accurate readings starting at the battery.
Like I said your charging voltage is low but I am assuming that is on your bike volt meter.
You sound like you have a little electrical experience but letís start with the basic, let me explain what we are looking for.
We are looking for a voltage drop, this can be on the feed side or ground side. A voltage drop is caused by a restriction in a wire or connector. Imagine you have  a wire with ten strands and six of them are broke, if you are running one light then there is enough voltage going through to light the light. If you add another light then that break restricts the current/voltage and acts as a resistor and the first light will dim. A bad connector with a corroded contact can act the same way or a bad connection from the wire to the contact in the connection can do this, it is resisting the voltage and you get a voltage drop. If one of your components like the coil is on that circuit then the voltage will drop and cause a problem.
This is why we start with just a good look at the wiring and start cleaning connectors, pull them apart use a good electrical contact spray and then pack it with dielectric grease. Dielectric grease does not help the connection it keeps the contact from corroding.
Any time you get resistance in a circuit it is going to create heat, that is why you will see a connector that is burnt up, it gets corroded resist the voltage gets hot and ruins a little more of the contact area and it gets hotter then it lets the smoke out. And we all know about letting out the smoke, yea a little geek joke.
You will be able to feel the heat anytime you have a restriction in the wire, run both sets of lights with the bike off and go around and feel wires, connectors to see if they are hot, a friend who does this for a living uses an thermal temperature gun to check for hot spots.
You are looking for any corroded connections; any places where the wires are moving back  and forth and can break a lot like on the side by the steering head going up to the key, front.
Oh yea it could also be in the fuse box, clean, check voltage both sides of the fuse.
Usually the problem is fixed without even knowing it just by doing a inspection cleaning.
Connections are the most neglected area of a Harley, remember these are not gold plated, and they are exposed to water, maintenance of the connectors should be a regular part of bi yearly maintenance.
The problem is going to be on a circuit that is shared by the extra running lights and something in the ignition system causing it to miss.
Let me look at your schematic to see what circuits to double check. Itís going to be somewhere from the regulator to a circuit that runs both running lights and ignition, or the ground. (something we have a tendency to forget)
And no, you did not offend anyone, we are used to posters coming in and asking questions not getting back. It would be nice if after the problem is fixed regardless if we helped or not you let us know.
Edit, you have circuit breakers not fuses.
The problem could also be from something using excessive voltage but I would start with the wiring.
« Last Edit: May 29, 2018, 05:14:48 AM by Harley_Cruiser Rocker Lockers »

Offline harley_cruiser

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Re: 85 FLHTC misses under electric load
« Reply #20 on: May 29, 2018, 06:06:00 AM »
And  check voltage at your coil, white wire, light off, lights on bike running
« Last Edit: May 29, 2018, 06:25:55 AM by Harley_Cruiser Rocker Lockers »

Offline jroestreich

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Re: 85 FLHTC misses under electric load
« Reply #21 on: May 29, 2018, 06:40:27 PM »
OK, that was a mouthful Harley_Cruiser Rocker Lockers.  Thanks for the insight.  I was at the garage today and did a couple things that were suggested here.  Had a new VR ...(don't ask.  My wife says I got more money than brains for this bike). I installed it and the chrging went to 13.7-14 volts at idle nothing on.  Turned on the head light and it dropped to 13-13.2.  Added the passing lamps and it dove to 11 10.5 and started missing.  Shut 'er down and disconnected the headlamp as was suggested.  Fired it back up and turned on the extra lights with no headlamp installed.  and it still was missing.  I reconnected the headlamp so I could see it and started it again because I wanted to check for dimming of the light when I added the passing lamps.  There was no dimming.  But there was missing.  I checked voltage from the battery positive post to all the places the ground wire connected to something at the back end of the bike and under the seat.  I was getting 13.2 volts at the terminals and 13.2 at every point along the way.  Then I did the same with the positive cables to solenoid and anyplace it connected and all the readings were 13.2.  I put the headlight back together and the seat back on and decided to ride it around to see what would happen.  Initially the bike was not responsive from a stop.  Throttle response was poor.  But after riding it a while that cleared up and the bike acted like its old self.  The voltage was good on the voltmeter in the dash so I started adding load and while it ate up voltage from the meter I was not getting the missing I had before.  I had every light on and no missing and at 1500 RPM or higher the volt meter was 12-12.5 or so.  At idle the voltage was 11 but that was how it always acted with all the extras on.  If i reved it the volts rebounded to 12.5 or so.  I don't think this is resolved by any stretch.  It is just hiding as these things do.  Would you concur?  Gotta adjust the clutch again after having it loose to replace the stator.  I'll ride it some more and see what happen.  Harley_Cruiser Rocker Lockers your list of things to do are awesome.  I will definitely work the list so I don't have these issues from poor maintenance. 
« Last Edit: May 29, 2018, 06:58:14 PM by jroestreich »

Offline rageglide

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Re: 85 FLHTC misses under electric load
« Reply #22 on: May 29, 2018, 08:20:59 PM »
If you aren't seeing 14-15v max when revving above idle you have a charging problem.

One question i have not seen asked or answered.    OEM ignition or Aftermarket?   OEM electronic can fire plugs clear down to the lower 7V range.   ALL aftermarket electronic ignitions are flakey or DOA once voltage is in the low 9.x Volts.   Usually this a problem presented when starting because a starter can pull voltage into the low 9's causing the ignition to not fire.  If you are breaking into the low 10V or lower while riding you will have ignition problems.

Offline jroestreich

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Re: 85 FLHTC misses under electric load
« Reply #23 on: May 30, 2018, 03:21:30 AM »
If you aren't seeing 14-15v max when revving above idle you have a charging problem.

One question i have not seen asked or answered.    OEM ignition or Aftermarket?   OEM electronic can fire plugs clear down to the lower 7V range.   ALL aftermarket electronic ignitions are flakey or DOA once voltage is in the low 9.x Volts.   Usually this a problem presented when starting because a starter can pull voltage into the low 9's causing the ignition to not fire.  If you are breaking into the low 10V or lower while riding you will have ignition problems.

stock ignition. 

Offline bagga

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Re: 85 FLHTC misses under electric load
« Reply #24 on: May 30, 2018, 04:43:27 AM »
OK, that was a mouthful Harley_Cruiser Rocker Lockers.  Thanks for the insight.  I was at the garage today and did a couple things that were suggested here.  Had a new VR ...(don't ask.  My wife says I got more money than brains for this bike). I installed it and the chrging went to 13.7-14 volts at idle nothing on.  Turned on the head light and it dropped to 13-13.2.  Added the passing lamps and it dove to 11 10.5 and started missing.  Shut 'er down and disconnected the headlamp as was suggested.  Fired it back up and turned on the extra lights with no headlamp installed.  and it still was missing.  I reconnected the headlamp so I could see it and started it again because I wanted to check for dimming of the light when I added the passing lamps.  There was no dimming.  But there was missing.  I checked voltage from the battery positive post to all the places the ground wire connected to something at the back end of the bike and under the seat.  I was getting 13.2 volts at the terminals and 13.2 at every point along the way.  Then I did the same with the positive cables to solenoid and anyplace it connected and all the readings were 13.2.  I put the headlight back together and the seat back on and decided to ride it around to see what would happen.  Initially the bike was not responsive from a stop.  Throttle response was poor.  But after riding it a while that cleared up and the bike acted like its old self.  The voltage was good on the voltmeter in the dash so I started adding load and while it ate up voltage from the meter I was not getting the missing I had before.  I had every light on and no missing and at 1500 RPM or higher the volt meter was 12-12.5 or so.  At idle the voltage was 11 but that was how it always acted with all the extras on.  If i reved it the volts rebounded to 12.5 or so.  I don't think this is resolved by any stretch.  It is just hiding as these things do.  Would you concur?  Gotta adjust the clutch again after having it loose to replace the stator.  I'll ride it some more and see what happen.  Harley_Cruiser Rocker Lockers your list of things to do are awesome.  I will definitely work the list so I don't have these issues from poor maintenance.

are you using the voltage reading from the HD volt meter on the dash? the HD volt meters are notorious for being inaccurate. i have an 85 and the meter isn't even close to being accurate. if you can rig up a hand held meter directly to the battery it would give you an accurate reading. i say the 15 amp circuit breaker in the ignition circuit is going south. i changed mine out about 10 years ago because it was giving me problems. i changed everything in the ignition circuit except the breaker, i studied the schematic until i finally seen the circuit breaker and realized it was the only thing i didn't replace. i changed it out and my problem went away. i actually changed all three 15 amp breakers under the speedo/ tach.
1985 flhtc
1976 fxe