F650GS intermittent starting problem

[seahorse]

Ok, bit of a saga this one.
For some time I have been having intermittent starting problems. The bike either fires up straight away as it should, or will sometimes not respond at all when starter button is pressed - no click, nothing at all. If this happens, it will often spark up as normal the next time I try it. There is no pattern to it at all.
I have tried different starter motors and relays. I now have the original starter circuit bypassed. I wired in a simple starter button as used on dirt bikes and now have heavy duty cables direct from battery neg to starter casing, from battery pos to relay, and from relay to starter. This appeared to work but the problem has returned.
Jumping the starter motor direct from the battery always works.
I can only conclude now that the fault may be in the ECU and am fast approaching the point of giving up completely.
Any suggestions gladly accepted, or make me an offer if anyone fancies e project or needs a 650 for spares!

 

[steve hughes]

Silly question but its not a faulty side stand or clutch lever sensor is it. Both would stop you starting and would yield no clicking. My Kawasaki was plagued with bad starting due to a faulty side stand switch.

Easy to verify when bike wont start, try starting with stand up and clutch in.

Good luck with your fault finding, intermittent faults are undoubtedly the worst.

 

[seahorse]

Good question but I have checked both of those.

 

[Bem]

FWIW my money would be on a broken/breaking wire between the starter button and the main loom. Turn the handlebars just a fraction and....

 

[squibb34]

So we have a 2012 F650GS with 76k+ miles & an unresolved starting issue that you mentioned last year.

Most options were explored last time, but I am not sure whether those were all checked out. Presumably there are no codes, the dash is completing the normal check procedure once only, with no EWS message & stays lit throughout when the bike is keyed on, with the neutral light showing & the clock maintaining the correct time, all the time.

Major suspects are unchanged, the starter button/kill switch, ign switch or attendant wiring, the side stand cut-out system, starter relay, poor earth/neg connectivity, a crank/cam position sensor going bad or could it simply be the battery itself, incapable of delivering sufficient voltage for the ECU to allow a start...sometimes. Some riders have found that their alternator stator has been cooked, along with a reg/rec failure, so once hot the bike is failing to charge the system adequately.

Perhaps you could clarify what has been checked recently please.

Personally I dislike the idea of running some form of starter cheat device, other than as an emergency measure, without finding the root cause with absolute certainty.

 

[Greenman14]

If it’s an intermittent fault how can you be sure all your tests were valid? Step by step replacement of each potential point of failure, then using the bike as normal for as long as it takes to either have the fault reoccur or to be happy that it won’t.

 

[een705]

Had a similar problem and it turned out to be gear potentiometer but that was on my f800