Random Starting problem

[Jonno]

Bike: ZX9R B2

Symptoms
Bike cranks as usual, has fuel, no start.(fuel fumes from exhaust).
Issue appeared suddenly 2 days ago, randomly will start and run as usual, doesn't cut out or is any different while it's running, and always starts again if it is warm.
But leave it overnight or for extended periods and is cold, the issue is there again.
Leave it for a bit, scratch ear, then head and arse in sequence and it starts, problem is I forgot if it was ear first, elbow next or was that my head or arse last!
Not saying this is "always" the way, just haven't had enough incidents to say anything else.

My Useless attempts so far:
I have tried switch block contact cleaning and that resulted in 10mins of fiddling about getting throttle cable back in wiggled any wire looms that I think are related, checked fuses, battery connections, starter relay under seat near battery (well it looks ok and has a click sound when activated).

The side stand switch I will investigate later as well as the clutch lever switch once a multimeter has arrived etc. The only thing that has been noticeable for the last few months is what sounds like a buzzing sound near the battery (thought twice about saying under the seat) every now and then but I am not sure if this is related as it cranks at good speed. Seems like it isn't getting the signal to ignite?

Is this an issue with heat/cool in an electrical component which doesn't make sense to me, although solenoids can play funny games?.

From what I have researched so far I suspect the CDI and it seems the starter and ignition circuits are in the same box?

I don't have a manual for it so I am guessing more than I would anyway,

Thanks if you can help.

Cheers

[seiko1]

Could be CDI but they usually just Stop and thats the end of it
Could also be a lack of use
Coming Tuesday MF?

[MickLC]

The B2's have the two coils under the tank don't they? Went it doesn't want to start are all the header pipes cold or only two? If it's only two are they off the same coil and does switching the coils make any difference?

[Jonno]

The B2's have the two coils under the tank don't they? Went it doesn't want to start are all the header pipes cold or only two? If it's only two are they off the same coil and does switching the coils make any difference?

No, headers would be all cold.

aw yeah, will go check once I find my tank removal socket.

[mick_dundee]

Had the same issue with my 9 shortly after I first bought it, after spending a shitload at the local auto elecy for no use, borrowed some bits from slow and wobbly's 9, coil strips and shit like that, in the end I bought another cdi and not had the prob since. Still got the old CDI if you want to try it off a c series though.

[Jonno]

Could be CDI but they usually just Stop and thats the end of it
Could also be a lack of use
Coming Tuesday MF?

Yeah weird thing really, have quite a few more ideas now so will spend the arvo checking things out.
Could be a slightly old discharged battery?

Working flat out at the moment, aint going anywhere.

[Jonno]

Had the same issue with my 9 shortly after I first bought it, after spending a shitload at the local auto elecy for no use, borrowed some bits from slow and wobbly's 9, coil strips and shit like that, in the end I bought another cdi and not had the prob since. Still got the old CDI if you want to try it off a c series though.

Thanks Mick, will keep that in mind, I have 2 other CDI's although not locally available, both off ZXR750's of varying vintage, I do know 1 of them is proven to work on this engine.

[adge82]

You have done the simple stuff yeah?
Checked your air filter and sparkies and confirmed 100% its getting fuel?

[Jonno]

You have done the simple stuff yeah?
Checked your air filter and sparkies and confirmed 100% its getting fuel?

Yeah..
With Oldmates help and swapping out parts, we worked out it was a "Loom Ghost" that has now gone away.

We know it isn't:
Fuel system
Coils
Battery
Plugs/ leads
CDI
Loom from CDI to Coils.

Problem seems to be before CDI and after Starter relay, so maybe a bad connection (which we contact cleaned everything), battery was at full charge. Was chasing wire colors in the loom between relay and CDI whatever, gave the starter a quick flick and it started, and has started since, and continues to start... farken yay

I suspect it will come back as we didn't fix anything.


Cheers everyone

[Smitty]

dodgy relay Jonno???? (or dodgy connection to it?)

[Jonno]

Of same mind and suspicious of the relay, main power and loom plug connections looks really clean and I fiddled with it - still it cranks over and no ignition, maybe worn insulation on a wire in the loom from there and dirty pin-outs in a connector even. Certainly isn't a component fault further along the circuit IMO as we swapped them all out and back again. Just after messing with loom 8" down to/from CDI it started and no issue since


Problem is now that it is starting it is hard to chase and isolate the fault. If it didn't start I was about to do a series of continuity tests, doubt doing that now will pick up much, could be wrong though



I would appreciate a schematic if any ones got one?

[adge82]

I have one for a C model, i imagine theyll be close.
Let me know if ya want me to scan it and post it up.

[dave#3]

Had the same issue with my 9 shortly after I first bought it, after spending a shitload at the local auto elecy for no use, borrowed some bits from slow and wobbly's 9, coil strips and shit like that, in the end I bought another cdi and not had the prob since. Still got the old CDI if you want to try it off a c series though.

Thanks Mick, will keep that in mind, I have 2 other CDI's although not locally available, both off ZXR750's of varying vintage, I do know 1 of them is proven to work on this engine.

It sounds like you didn't need to use the CDI's anyway, but for others reading remember that the zxr750 CDI has a higher rev limiter than the zx9r B engine is designed to run to, and running this CDI may well end up in a short-lived engine

[oldmanmike]

Had a similar problem with my B1 when I had it. Turned out to be a dead/dying diode in the junction/fuse box under the seat. You have to pull it apart to get to the diodes. There are 3 in line in the start circuit (G/BK - BK/Y ).

I have the B manual as a pdf. 133MB so you would need to give an addy for cd & snailmail if you want it.

ignition diagram_zx9rB.jpg (75.67 KiB) Viewed 1916 times

[Jonno]

UPDATE* Had no issues since which is good and also a concern as to why it happened and possibly returning

It sounds like you didn't need to use the CDI's anyway, but for others reading remember that the zxr750 CDI has a higher rev limiter than the zx9r B engine is designed to run to, and running this CDI may well end up in a short-lived engine

That is correct
I also have been told it raises idle a few hundred as well.

Also C model CDI is totally different just like most of that bike.

Had a similar problem with my B1 when I had it. Turned out to be a dead/dying diode in the junction/fuse box under the seat. You have to pull it apart to get to the diodes. There are 3 in line in the start circuit (G/BK - BK/Y ).

I have the B manual as a pdf. 133MB so you would need to give an addy for cd & snailmail if you want it.

Thanks mike for the heads up

I will take you up on that kind offer