While cruising yesterday my engine intermittently cutout. I was able to observe the tachometer indication. At cruise I was at approximately 2600 rpms. When the cutout would occur the tach would jump to 4000+ and back down below 1500. The actual rpms of the engine just coutout when the tach indication dropped. The engine never completely quit. It happened 4-5 times and I turned and headed for home.

This happened once right after I got the bike. I switched from bright to dim on the lights coming to an intersection then the engine cutout and the lights went dim. It was only momentary. I didn't notice the tach indication. Not sure if this was coincidence or symptomatic.

1992 FLHS 46k miles, new battery, all other components original. I unplugged the voltage regulator plug/connector and one of the pins was heavily oiled. All connections seem tight and not corroded.

thanks for your help in advance
Brett in Boise

 

i would clean up the pin with the oil. then to me, i think its ingntion related, ck cam sensor by jiggling the wire that comes out of the nose cone. if the motor stalls youve found it. could be the module as well.

 

The tach is going to be a good indication of how the ignition is acting but then again if the bike is cutting out it aint going to act proper meaning jumping up and down although I can't see why it would jump up. I'd check wiring to ignition especially where wires are near front pipe as well make sure all is fine in the cone at the ignition pickup and cup. I had a cut out ( complete shutdown ) earlier in the year when I fiddled with the lites and found that when I did some rewireing I put too much on one of the circuit breakers which are in the bat wing.

 

Thanks for the tips. Lynn I read your troubleshooting post. It helped a bit so far.

Do the wires have to be off the coil to do a resistance reading? With the wires attattched I get 3.8 ohms(spec is 2.5-3.1).

The one instance that it happened while switching bright to dim sent me down one path in the electrical diagram. The orange wire coming off the tach does end up travelling to the 15A accesory breaker where the dimmer switch goes to. Don't know if that is where I should focus.

thanks
Brett in Boise

 

Brett,

It sounds similar to problems I had with my '90 FLHS some years ago. The problem eventually solved itself when the ignition sender in the cone failed completely! So that is another candidate. Not sure how it can be checked though.

 

Brett the troubleshooting steps you seen were probably a quote from Dr Hess , he's the goto guy for that stuff.

 

If it weren't for the tach indication I would think it was purely the ignition circuit. It would seem that I'm losing power to the ignition and light breaker relays.
At this point I'm thinking sensor or module. I'm going to try the blow dryer/heat gun on the sensor to see if I get the failure.

 

Just my opinion but I think the bump you saw in the rpm on the tack was not from motor jumping to that RPM but the impeadence bump the tact received from a misfire of the plugs or wires. The bump proves there was fire. Unless you know for sure status of plugs, replace them and check ohms resistance of wires. Wet your hand (might want to get you best squeeze for this) and run them up and down wires while running will check insulation. Running it at night in the dark is also a good way to check and less painful.

 

Bad voltage regulator will throw off the tach, too. Low voltage will make the bike cut out. Doing a reality check on the charging system is a good start and only takes a few minutes. I should bookmark wherever on here my charging diagnostic instructions are, but if you search for them, they should show up. Search for "How To Diagnose Your Charging System" in the Evo forum.

 

Thanks all!! Will report tomorrow.