auto/motorcycle electrical question

[ned]

Since this forum has more pin ball wizards than Google.....I am being out smarted by a Buell motorcycle.
It runs, then it stops dead. New battery, cleaned all the grounds, replaced ECM twice....Got to thinking it was the alternator..
I attached a volt meter to the battery terminals, instantly showed 13.5 volts, good. Started engine, voltage did not drop while activating the starter, the voltage remained at 13.5 with the engine revved and stayed at 13.5 at idle. Needle on the voltage did not flicker even when the high beams were flashed and after running the bike for about ten minutes at 2000 rpm the voltage had not moved off of 13.5.
I must be doing something wrong either with the VOM setting or how I am using it....any ideas welcome. I would have expected the voltage to drop at idle. Thank you, Ned

 

[JFB]

I had to make a double take. . .
on a car forum a two trouble shooting took place having owner stumped, only to find out the DMM was defective and not showing correct.

look to see if your meter has a "Peak Hold" function, where display locks to highest voltage measured.

if you turn on headlight (with out engine running) does 13.5 dip

a fully charges battery will be about 13VDC not running. a charging alternator should keep voltage higher during the majority of running conditions (some times full lights at idle if alternator is undersized)

 

[Captain America]

To check the stator put the meter on AC and put the leads in the two wires going into the voltage regulator. You should get about 10v per 1000 rpm, 13.5v DC is fine at the battery and that shows that the voltage regulator is grounded properly and working. You said it stops dead, are you saying the battery goes dead and you need to charge it or does the engine shut off and won’t restart...what year Buell?

 

[ned]

Thank you .....bike quits, all dash lights etc. off...after a few minutes all comes back...but no cranking...assumed ECM but unless I got two bad in a row....new battery, now starts, runs up and down the street for a while then quits...thought it was running off the battery so that was why I was trying this experiment...will check peak hold function on this 40 yr old VOM that has not been out of box for 38 yr

 

[Fox Mike]

Out of curiosity, how long does it run before it stops? Something "heat sensitive" would be where I would be looking.

 

[coach]

It’s my understanding most charging systems work at about 14.5 volts. 13- 13.5v is more what float chargers use. I have had control module on a lawn tractor quit when it got hot. When cooled it would work.

 

[Skidboot]

Not sure about Buell's, but some Harley's have main circuit breakers that are defective or overly sensitive to heat. They get hot, and the bike will totally shut down. When things cool, the bike will start again. Just a thought.

 

[Dan in MI]

I know zero about bikes, but a lot on cars/trucks. The two suggestions about heat sensitive items sounds logical to me. Whatever it is runs great cold as it warms up it quits. let it sit and then it works again. Alternator/battery would not do that, especially not that quick. There was a time when ignition modules were known for just what you describe.

What else is there electronic/module wise in the system? Does it have a separate ignition module, fuel pump module etc... What type of circuit protection? Do bikes have thermal fuses (like windshield wiper circuits) That sounds more like it as I think about it. A breaker requires you to reset a thermal does it on its own.

When it quits is it just quit or slowly die?

 

[Captain America]

OK, so it’s not a charging problem, when you say ECM are you talking about the ignition module on a carbureted bike or the ECM on an injected model...what year and model?

 

[chm270]

My Sportster was doing the very same thing..
All battery connections nice and tight.
BUT..
I was WAY out in the country in MN and the bike quit.
No choice but to mess with it and try to get it started..
What I found was that the negative lug was tight at the frame, but it was actually broken and held together by the shrink wrap at the end of the cable.
PULL on those battery cables. They should be good and strong.
Edit:
The reason these connectors break is that 1) They start out as copper tubing, then one end is mashed flat and a hole drilled into it.
Where the "pinch" is is usually where they break.
Caused by 2) Vibration of the bike, and if you were to notice, (easier to see on a car battery)
When you hit the starter, the cables actually "jump" slightly. Over time this is constantly bending the lug at that weak point, and eventually it can break.

 

[ned]

Thank you all.....it is an ECM, fuel injected bike....will research for what might be heat sensitive ..thanks all.
The failure mode is sudden, complete and dash lights come back in 10 minutes...., will start 30 min after that.....got to love an intermittent ...then it will run again for 10 minutes or so....rinse and repeat.....
PS my 85 FXSB died this week too....might be the cycle of the moon....in that case it was exactly what chm270 said...broken ring tongue term on the negative post of the battery.....got to love this rolling stock....

 

[graygun]

Have you tried the Buell forums ?

 

[Mega Twin]

Like was said above, check all the connections,not just wiggling them,but take them loose
and make sure they are clean and tight.
A bad electrical connector will often show as the plastic being melted or discolored.

 

[daveg.inkc]

Thank you .....bike quits, all dash lights etc. off...after a few minutes all comes back...but no cranking...assumed ECM but unless I got two bad in a row....new battery, now starts, runs up and down the street for a while then quits...thought it was running off the battery so that was why I was trying this experiment...will check peak hold function on this 40 yr old VOM that has not been out of box for 38 yr

I had the same problem on a 1986 883 Sportster. Bought new, no miles, from Yeager HD in Sedalia, MO. It would die and only way to keep running was to hold a turner signal on. Crazy, huh? I traded it in 1988 for a FXRT. Eric Buell designed. I think it was the computer ignition. Next owner of this problem bike installed points. With this XLH, I would press a turn signal and motor would quit sputtering. Till one hot afternoon, it died, I pushed on shoulder of highway and said enough. I rode a big twin home.

 

[ned]

my FXSB (evo with kick start) has had very few problems in 35 years...but they have all be electrical... I still have points.

 

[graygun]

I have stuff with points but not cycles.

Let us know if you fix it.