Bike cuts out after revving
 

Hello,

Have a K5 that is stalling/enging cutting out, after revving.

At idle, it seems to be ok, sitting at around 1500, but after revving it, it drops below that, sits at 1000-1300, sputters and cuts out (while in neutral, 1st with clutch in etc).

Happened first time about a couple weeks ago, after fueling at a Sainsbury's. Thought it might be bad fuel, but the station claimed they didnt have any other such complaints that day.

Removed the fuel, added new fuel with some Seafoam, and bike ran like new.

A couple weeks later, and the same problem is back now, and got stuck far from home so called RAC. They did a hard reset, but no joy and "suspect fuel issue".

Any thoughts?

And while I appreciate its hard to diagnose something remotely like this, would anyone have any recommened mechanics in the south west london area?

Many thanks in advance.

Re: Bike cuts out after revving
 

One thing to rule out is a blocked breather in the fuel cap. Easy to check, just open the cap and see if anything changes. I'm also wondering if the fuel pump has picked up some debris.

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Re: Bike cuts out after revving
 

Is the bike stored outside? I had an issue where the tank drain tube was blocked which allowed rain to make its way into the fuel causing issues on my gen 1 bike. Could be worth draining the tank again, but into a container to see if you have any water in your fuel. The water is heavier, so sits at the bottom

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Re: Bike cuts out after revving
 

thanks for the quick replies, much appreciated.

John - tried it (running without fuel cap), and bike still cuts out after revving engine. i get plenty of pops from exhaust suggesting (by my novice thinking), that the bike runs rich more than lean.

mister c - dont know if my K5 has tank drain tube, but happy to check. looking into it. will drain tank again as suggested, but might not be a few days, so will get back to you with results.

Re: Bike cuts out after revving
 

This hole has a pipe that goes inside your tank & should exit at the rear. They sometimes get blocked, or the rubber drain hose that's attached to it gets crimped which then allows water to build up around the filler, then drops into the fuel tank. I'm not saying that's the issue, but could be worth investigating.Attachment 16931

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Re: Bike cuts out after revving
 

popping on the overrun is caused by a lean mixture, usually an intake air leak but (less often) an exhaust leak.

Do your secondary throttle butterflies do their start up dance?

https://www.youtube.com/watch?v=2dkXIIf7U20

Re: Bike cuts out after revving
 

another cause could be the battery is past its best or the terminals on the RR connector. this sound the same symptoms i had and it turned out to be the RR connector.

Re: Bike cuts out after revving
 

[QUOTE=mister c;3142757]This hole has a pipe that goes inside your tank & should exit at the rear. They sometimes get blocked, or the rubber drain hose that's attached to it gets crimped which then allows water to build up around the filler, then drops into the fuel tank. I'm not saying that's the issue, but could be worth investigating.Attachment 16931

thank you mister cc, it seems ok (i think), but havent checked the hose beyond just checking the opening. what does worry me, is the appearance of light rust around the fuel intake, which I'm looking into. Will have to drain tank and clean it.

Re: Bike cuts out after revving
 

Thanks Bibio, have checked battery and voltages are:
12.54 when off
11.98 when ignition is on
drops to low of 8 or 9 when starting up and runs at 14.4

seems ok, i think...perhaps too high when running? or too low when kicking over?

Re: Bike cuts out after revving
 

Cheers Seeker. Here's a vid of the attempted dance of the butterflies. Doesn't look as impressive as those in your vid, so perhaps that's indication of the issue I'm experiencing...

https://www.youtube.com/watch?v=1Nui5QjOEO8

Re: Bike cuts out after revving
 

14.4v is fine.

Re: Bike cuts out after revving
 

I believe the full travel of the butterflies is necessary to confirm the correct span readings from the position sensor and if thats not achieved I would have expected it to throw up a fault code...

Re: Bike cuts out after revving
 

"The best way to get correct information on the internet is to post the wrong answer".

So with the above comment in mind: I think the stv butterflies should be fully closed with the engine off. When the ignition is turned on the stv butterflies will rotate to their fully open position and then set themselves depending on engine temperature, but I have never needed to play with them...

...you should get an error code/FI light if they're not working correctly.

The stv butterflies are there to smooth the airflow and prevent stalling caused by a collapse of inlet vacuum as the main butterflies are opened quickly (based on what I've read).

Re: Bike cuts out after revving
 

yes there should be a certain voltage read from the STV position sensor by the brain at closed and then another at fully open. If these two values seen in the test arent within limits it should give a fault because otherwise the brain cant position the butterflies correctly...

Re: Bike cuts out after revving
 

I suppose if there was a lot of mechanical slop (tech term) the stv motor could run through its travel but not actually move the butterflies?

Re: Bike cuts out after revving
 

well the movement sensor is on the other end of the STV so the motor can do what it likes but its the butterflies (well at least their shaft) that have to move to produce the correct signals...

Re: Bike cuts out after revving
 

battery should not drop to 8-9v when starter is pushed. it might run at 14.4v (RR doing its job) but battery might have dodgey cell. my battery exibeted the exact same symptoms of looking fine.

i think if you have run out of all other options then a new battery, remember its winter and it kicks shizz out of battery.

Re: Bike cuts out after revving
 

thats not right. they should move as in the other vid seeker posted. make sure that nothing is fowling the link bar as it looks jammed to me.

Re: Bike cuts out after revving
 

Cheers. I have already dropped it off at mechanic to look at, and they called to say battery, etc all looked ok. perhaps the 8-9V occured once (was momentary, and I'm jumping at everything at this point)...but I will check again and let them know.

I checked the STV's a second time before taking to shop, and they seemed to function ok but bike still cutting out.

Thank you guys for your help. The feedback I got from shop, was potentially some issue with valves and they're checking that now. The 16k service wasnt done (and I had no idea this was needed till now - although seeing there's a bit of debate on that) so hoping its the right idea and its not too expensive.

Re: Bike cuts out after revving
 

Or just buy a Gen 1.... Carbs are king :)


Only joking. Hope it gets sorted quickly

Re: Bike cuts out after revving
 

Picked up bike, it seemed to run fine. They went through a few things, but settled on cleaning out injectors, which had accumulated a significant amount of black stuff, and werent operating right. Would spray way too much fuel (could even smell it when riding).

Riding it normally, gives a fun melody of decel pops, but this time it did "backfire" pretty loudly once, which got me worried. That would previously happen just before the engine would cut out.

For about an hour, I was riding without further issues.

Then I pulled over for a bit, paused for a few hours, and set off again, and this time it cut out twice, just as before. I turned off engine, paused for a few minutes, and set off again, giving it as much throttle as I could. It went fine.

Called mechanic and the recommendation is to replace throttle bodies. I suggested battery change (thanks to Bibio's suggestion), and was told its not needed. But i feel Bibio may be right. Time to order a set of throttle bodies and a decent battery.

Re: Bike cuts out after revving
 

:D yeah, always wanted a curvy because felt they were just so unqiue looking and beautiful. Not sure how I didnt end up with one.

Re: Bike cuts out after revving
 

Ok so the saga took a nastier turn, and its all about rust.

My tank was rusting and the fuel pump is a heap of **** loaded with rust and working from time to time.

So I am in search of a K5 compatible fuel pump replacement (£1000 new).

If anyone else has the same sort of issues, I recommend the moment mechanic suggests looking at injectors, you get them to check fuel pump first.

Cheers all. Hope to have good news soon.

p.s. If anyone has a fuel pump they're looking to sell, give me a shout (although looking to buy one today).

Re: Bike cuts out after revving
 

I may have got something wrong but listed on ebay for about £50 for a K5

Re: Bike cuts out after revving
 

Thank you redtrummy. got one from ebay, and its on the way.

Re: Bike cuts out after revving
 

Any progress on this then kickaha?

Re: Bike cuts out after revving
 

hey thanks for checking back. no change yet, as its getting repaired today (head mechanic works mon - wed).

hopefully I have good news by end of day, so unless I hear differently, the solution was:
- replace fuel pump
- clean injectors (again)
- finish cleaning tank (was in process from last week)

will update once its done.

Re: Bike cuts out after revving
 

Excellent, thanks for the update.

Re: Bike cuts out after revving
 

So nothing new today...the tank is still being cleaned. Previous efforts didnt get it perfect, so they're trying a new chemical and will update tomorrow.

Re: Bike cuts out after revving
 

And for the final post on this issue, as a thank you to everyone that helped, and just in case anyone has the same issue.

Verdict: rust in tank, blocked fuel pump and injectors.

Solution: clean tank, replace fuel pump (approx £100 on ebay, £1000 new from suzuki, take your pick), and clean injectors (using Fuel Injector Cleaner Kit).

That solved the problem, and am now running a responsive, fast and reliable bike again. Have just come back from the first long ride and its as good as new.

Thanks again to all that advised/helped, and many happy safe rides to all.

Re: Bike cuts out after revving
 

Hooray! Excellent news. Sorted in time for the summer! :-)

Re: Bike cuts out after revving
 

Good to hear, I bet you're relieved.

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