K5 cutting out on deceleration

[Hooli]

Chaps & chapettes....

I've asked this on FB last night so got a few ideas, but asking here as it's the real place for 14 knowledge.

The friend's K5 I did loads of work on last year has gone back to it's tendency to cut out on deceleration, she can feel it die so it's not firing as if the ignition has gone off when it happens. It can't be the usual tickover as it happens when the revs are higher & the clutch is engaged.

It's random, happened three times yesterday but didn't at all for a few rides before that. Normally pulling the clutch in & hitting the button fires it straight back up, she's not tried seeing if it bumps but sounds like it won't from her description.

My first thought was the immobiliser recall, if that was cutting the fuel pump/spark then that'd explain the issue. We're going to check if her bike has been done. It never fails to start or recognise the key though.

Other suggestions from FB are the clutch & tipover switches. I'll try a new clutch switch on it as it's so quick to do, someone has said they've had the spring inside fail so the switch flickers on & off when riding. I guess the starting map could flood the engine as it was never designed for deceleration, but that's a guess on my part.

I know vacuum pipes, TPS etc are all ok as I did them late last year & it's not done a lot of miles since. This problem was happening at times before I did all the work last year too, I thought I'd solved it when I found split vacuum pipe but it seems not.

Any thoughts?

[KiwiCol]

None really other than you've mentioned, but please keep us informed as to what is was, I'd like to know.

[AndyB]

I'd go with the clutch switch too hooli....they are a fookin nightmare especially if its intermittent.....I always carry a genuine Suzuki spare....

[Kiwifruit]

That sounds like the issue I had for ages. Was a real pain. Intermittent so a nightmare to find. Sometimes it would run fine for three weeks. Had some clued up guys look at it to no avail. Replaced the clutch switch and thought I'd fixed it then it did it again so not that. I'd be decelerating and the engine would be lifeless, arrive at a stop and the engine would want to cut out. If I could catch it I could keep it running at about 3-4k. So finished up sitting at the lights like a goose with it revving it's tits off. Makes the bike damn near unridable.
So I pulled all the multi plugs apart that I could find and cleaned them up with contact cleaner. Eventually I pulled the headlight out and did the same in there. My belief is that one of those was the problem. Hasn't reoccured. Hope that makes some sense. That's my two bobs worth Hooli. Best of luck finding it.
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[Hooli]

Cheers chaps, I'll let you know how I get on with it.

[Hooli]

Small update, it's not the recall as that was done in 2007.

I've got another clutch switch that I'll stick on it when I see her next, probably this weekend.

[Eric GSX1400K3]

Could it be the pick up magnet on the timing wheel (rhs cover) ? On my k3 I know the magnet is broken  in half, but the retainer plate keeps it together, I'll have to replace it one day.  Could be that on deceleration (revs falling) that the timing pulse to the ecu gets lost or squirreled up, so then the ecu cuts ignition to prevent detonation.

Perhaps a check with an engine timing light, the strobe on a dark background, strobe speed should fall steadily in line with the rpm dropping, but a lack of signal would see it flickering.  Just thinking out loud...

[Hooli]

Interesting, I've not heard of that one before.

I'll try it, cheers.

[grog]

Good stuff Eric. Once had Mitsubishi work van , injected , kept cutting out. Ran fuel pressure gauge into cabin, also timing light. Found its problem, pressure dropping off. Turned out filter got heat soak from being too close to exhaust, factory fit. Moved it, wrapped it in  exhaust wrap , prob solved.

[Hooli]

Well I might have spotted the issue on this bike over the weekend at a rally, I was stood looking at it as you when muttering to yourself about daft problems you can't find when I spotted a vacuum pipe starting to split. I know I checked them last year& one had a slightly split end. They all felt soft & flexy though so I'd assumed I'd done it pulling them off, seems not.

When she lets me know she's free for an hour or so I'll go replace all the vacuum hoses & see what happens. Rather annoying if it is as I'd even got new hose last time in case it needed it & decided they didn't need swapping.

[Hooli]

Vac hoses now replaced on this bike, if the weekend is nice she should be out on it to see if it behaves.

Plan of action if it doesn't is replace the clutch switch as some people on FB have mentioned a similar issue caused by the return spring inside the switch failing so the bike drops onto the starting map at random. Then the tip over switch, it's got to be something daft doing it cause it runs so well the rest of the time.

[KiwiCol]

I very much doubt it'll have anything to do with the tip over switch Hooli, have a look at the schematic of the thing, as long as the bike is upright it can't cut the engine.  It'll cut it if she goes over, but stand it up again & this switch repositions itself & the bike will run.

It's gonna be those hoses -

[Hooli]

Aye I can only see it if the switch is faulty & that's why it's last on my list.