Pointy SV running on one cylinder intermittently.

Hi guys, bit of a long post but I'll start at the beginning just to lay it all out.

Firstly, bought the SV650 SK6 new in 2007 and currently only has just over 1600 miles on the clock as it'll get used 4 or 5 times at most a year!
Planned on getting a bit of use out of her over the next few month to rekindle the interest but this 'issue' is preventing that!

Towards the end of last year, I was getting the bike ready to be tucked in for the winter and though it'd be easier to get it MOT'ed then instead of having to do it before getting back on the road this year (just pay for 6 months tax online and it's on the road againl).
A couple of time on the way there it was lumping a little but I was putting that down to the old fuel, passed the MOT no problems and as I was heading back, thought I'd go the dual carrageway route to open her up a bit.
Gently wound the speed on and as I got up to around 65mph in 5th, it didn't seem to want to rev anymore.
Cogged down (to clear it out) and it immediately slowed, swiftly cogged back up and 'feathered' the throttle just to keep it going.
It was like the carb icing I used to get years ago on a GPX600, too much cold air and not enough fuel.
Nursed it home and tucked it in for the winter knowing it'd be something to look at this year.

Beginning of this week, a few litres of fresh fuel, fully charged battery and fired her into life, planned on taking her for a run to see if the 'fault' was going to be there.

Stone cold roar at 2500rpm for a few seconds slowly dropping down to around 1800 for a further few seconds (all as it normally would), then a cough, a second cough then decided to run at 1200 as a single for a couple of seconds, back up to two cylinder at 1700-1800 for a couple then back to one before I shut it off.
No problem I thought, at least there is definately a fault (no need to force it out), I'll just get the code and see what I need.
I shorted the block and got a c00 code.......
Okay, maybe a clogging injector.....Splash of Redex and after about 4 or 5 of the current signature start ups (ie runs for a handful of seconds then cuts a cylinder then goes back to 2...) realised that it isn't an injector so started thinking about a possible fuel pressure issue.

Removed the fuel pump, cleaned the strainer (found a small collection of silvery black debris inline with the intake and when sucking through it, it was 'trapdooring' so though it was the answer), gave everything the once over (all looks brand new), couldn't get the regulator out of the cartridge (and didn't want to force it after getting a 267 quote to replace it!) so put it all back together fairly confident that it'd be back to normal.
Fired her up, ran strong for a bit longer than the first time around, then coughed, coughed again, then dropped to one cylinder for a few seconds..........Balls!

Pulled the iridium tipped plugs out (been in there since the first week of ownership) and they were both wet and tan showing perfect running when the engine is firing.....

I'm pretty sure its a fuel supply issue.
If I switch off the ignition whilst on one cylinder, switching it back on results in the expected 3 second whine from the fuel pump and it starts up on two for 10 seconds before going back to one, then up to two, then back to one.....

I suppose as I'm writing this, if I killed the ignition with the kill switch then went back to 'Run' and buttoned the starter, I'd bypass the fuel pump doing it's 3 second priming and then I'd know if it's still low on fuel pressure by having it starting on one cylinder or going from two to one very quickly?
Something to try next time I wheel her out of the shed.

I've also just found a thread about disconnecting the Tacho on a '325 single' SV to bypass a shorting fault on the electrics, will try that too just for good measure.

Other than those two ideas, anyone got a direction for me to go?

If I don't get anything else to diagnose the problem, the next option is to buy an inline fuel pressure gauge and see for the pressure drops whilst the engine is running to prove if the fuel pump/regulator assembly is the culprit....
　
Jynx had an O ring seal fail and fall out on his SK4 which answer his problem on an issue that sounds similar to mine, this SK6 has a white plastic cartridge and a different design of regulator that didn't seem removable at the time of fiddling....

I think it's complete b*ll*cks that Suzuki won't supply the fuel filter cartridge without the fuel pump eventhough they are two separate components, anyone know of anywhere the cartridge can be purchased individually?

Thanks in advance,
Darren.

Test ignition coils.

Originally Posted by The Guru

Test ignition coils.

Thanks, will do on my way down to the fuel rail but wouldn't a faulty coil (even an intemittent one) by caught by the fault code system?
The battery hasn't been disconnected so all codes should be retained.

[rictus01]

the ECU has no idea whether the coil works or not, likewise the low tension feed wires, the plug cap or the plug, you won't get any "codes" for these, generally the "325cc" problem is electrical rather than fuel, as it's easy and fairly quick it's worth discounting these first.

Originally Posted by rictus01

the ECU has no idea whether the coil works or not, likewise the low tension feed wires, the plug cap or the plug, you won't get any "codes" for these, generally the "325cc" problem is electrical rather than fuel, as it's easy and fairly quick it's worth discounting these first.

Thanks, guessing the 'basic' FI system only picks up on sensor faults as opposed to voltage changes or pressure issues (if it did, it'd be able to tell me if the fuel pressure was low at either injector letting me know what was wrong!)

When it was on one cylinder, I pulled the front cap and it died leading me to believe the rear cylinder is the one 'missing'.

Looking at the fuel rail, the front cylinder would get priority if the pressure was dropping:

Can't understand why Suzuki didn't create a single, balanced rail without a bit of garden hose linking them......costing I suppose

Also, if the nearest in the picture (second in line) injector rail is hollow past the injector there's the chance of getting an air pocket and fluctuating pressure on the second injector.
With all the times old fuel has be allowed to deteriorate in the lines, minute bubbles could have made their way down there and be hampering it (very remote chance but something I'm looking at from a mechanical point of view).

Appreciate the info

[Bibio]

i've had this while mucking about and it was airbox hoses. it sounds like it firing on 1 then 2 but in fact its just getting confused. mine might be because it was a twin spark with auto idle but you never know. another thing you might have missed when installing the new plugs was that you must remove the nipples on the new plugs or the cap wont fit right.

firing on two then dropping to one sounds electrical to me as if it were fuel then it would be constant as the SV is a pressurised system.

careful with those iridium plugs as i have snapped/cracked a few at the top of the threads as they are made of cheese. no i'm not ham fisted.

Originally Posted by Bibio

i've had this while mucking about and it was airbox hoses. it sounds like it firing on 1 then 2 but in fact its just getting confused. mine might be because it was a twin spark with auto idle but you never know. another thing you might have missed when installing the new plugs was that you must remove the nipples on the new plugs or the cap wont fit right.

firing on two then dropping to one sounds electrical to me as if it were fuel then it would be constant as the SV is a pressurised system.

careful with those iridium plugs as i have snapped/cracked a few at the top of the threads as they are made of cheese. no i'm not ham fisted.

Thanks for the input

I've never dug any further than the top of the airbox (checked the original filter was clean and took part of the snokel off) so wouldn't expect a trapped or damaged hose but will check them all through.

Plugs have been on there since July 2007 (without nipples), have used them in everything since they came out, even have a set in the CR-V.

I'd expect an electrical fault to just stop a part working as opposed to fluctuating, the bike lives in the shed and only ever saw rain once towards the end of 2007 whilst I was clocking up some miles to get it in for the 1000 mile 'just run in' service (so I could cut the exhaust off and start using it properly).

The fact it runs perfectly for the first 10 seconds everytime after firing the fuel pump gives me 'old school' visions of a float bowl in a carb that is gettiing a gravity fed dribble from the tank which is enough to refill it over 20 seconds but not enough to keep the engine running, if you know what I mean

I've seen a few GSXR's with running issues that when the revs are wound on, the fuel pressure drops off (found a video on youtube with someone running a fuel pressure gauge whilst running the engine).
It shouldn't fluctuate at all but it does meaning either a weak pump, slow pump or programming issue.
The inline 4 cylinder engine just gets a slight misfire at higher revs which tends to be masked by the others still running but then the issue doesn't seem so bad as the injectors are supplied their fuel on a single, straight rail, not the half-*rsed looking 'Homebase' job I've found in the SV manual!

Maybe the combo of reducing fuel pressure and rail set up on the SV is making the issue pronounced enough to cause a cylinder to lose fuel for a second or two whilst the pump tries to keep up?
Seems to be more likely now as when it has dropped to one, I pulled the front cap and it died.
This shows it is the front cylinder that is keeping it going when down to one and that is the one that receives the fuel first on the rail.
Coincidence? I think not.....

[Bibio]

carbs and FI are completely different beast. FI does not have the backup of what's in the float bowl to run for a while. FI will either run or die as the injector is either open or closed to which fuel is squired by pressure. apart from the mantel in the injector being clogged i cant see how else there would not be fuel. and as you have said both plugs were tan and wet. which tells up that there is indeed fuel getting in to the combustion chamber.

9 times out of 10 its electrical with the SV. with suzuki electrics not being the best in the world it's more than likely a furred up connector. even a vacuum leak will not stop it running.

i would also not say that the fuel rail on the SV is half arzed as it works and works well and i have never heard of anyone having problems.

with a twin you can narrow things down easier than an IL4 as there are only 2 pistons.

have you tried a fresh set of plugs as its not the first time i have had plugs fail premature and yes even iridium ones.

Lots of talk, but have you checked those coils?

I personally know of about 5 different 2006/2007 K6 model SV's that have had this problem due to a faulty coil.

Suzuki went through a faulty batch of coils that year.

Sent from my GT-I9300 using Tapatalk 2

Originally Posted by Bibio

carbs and FI are completely different beast. FI does not have the backup of what's in the float bowl to run for a while. FI will either run or die as the injector is either open or closed to which fuel is squired by pressure. apart from the mantel in the injector being clogged i cant see how else there would not be fuel. and as you have said both plugs were tan and wet. which tells up that there is indeed fuel getting in to the combustion chamber.

I know they are completely different but I'm explaining that is what it 'feels' like, a fuel starvation then recovery then starvation......
The injector rail is much like the float chamber in this case, feeling like it isn't supplying enough fuel.....
Fair point both plugs were wet but I know they do get fuel as both are running just not constantly

9 times out of 10 its electrical with the SV. with suzuki electrics not being the best in the world it's more than likely a furred up connector. even a vacuum leak will not stop it running.

i would also not say that the fuel rail on the SV is half arzed as it works and works well and i have never heard of anyone having problems.

I meant the design looks half arsed, why not have gone with a single metal rail and a central feed than two rails, a feed to one and a bit of hose joining them?

with a twin you can narrow things down easier than an IL4 as there are only 2 pistons.

Agreed

have you tried a fresh set of plugs as its not the first time i have had plugs fail premature and yes even iridium ones.

I have the original plugs and they will be going back in when I go round to run through everything picked up in this thread, needed everyones view and ideas hence putting it up

Originally Posted by Fordward

Lots of talk, but have you checked those coils?
I personally know of about 5 different 2006/2007 K6 model SV's that have had this problem due to a faulty coil.
Suzuki went through a faulty batch of coils that year.

Will be checked as part of the 'fix', nice to know there have been faulty coils about, gives more credit to that being the possible fault, thanks


All info very much appreciated and if I do solve it, I'll be sure to go through what I did for future help to anyone who has this issue

Finding this to be a great forum and glad of the input