Frustrated

[ringfeder3]

Previously, I posted some of these symptoms under 'fuelling' but now I am unsure if the problem lies within that parameter,,

I have a 2007 GSX1400 which has been fastidiously maintained. It has 50000 km with a full Suzuki service history and has only been run on premium fuel.

Riding varies from short trips to 300 km. It has never been ridden hard.

Lately I have noticed a problem, which I will try and describe as best I can. Please bear in mind that I have a fairly rudimentary mechanical understanding of bikes...

I collected the bike from where it had been stored for 3 weeks and commenced to ride it 300 km home. For the first 20 km, I noticed some 'hesitation' in the acceleration. It felt as though there was some type of fuel blockage. This occurred at either low or harsh acceleration. After 20 km, the problem appeared to rectify itself and the bike ran well.

During several short rides in the following weeks, the 'hesitation' was apparent again. At typically lower (urban) speeds.

Following advice contained in other threads, I had the fuel pump removed and the filters checked. The 'tea bag' filter was clogged with grit and sediment and was thoroughly cleaned. The main filter was blown out with fuel and air and the tank reassembled.

For several weeks, the bike felt as if it was running better but lately, the problem has been recurring.

Under full acceleration, the bike goes well, but on the overrun, the hesitation becomes obvious again.

Under low acceleration, 1000 - 2000 revs, or idling, the bike feels like it is 'surging' slightly.

It revs freely and starts every time without a problem.

I have considered a replacement fuel pump/ filters but would have thought that if these were faulty, hard acceleration would cause the problem to be evident as well.

And wouldn't the use of premium fuel ensure that the injectors are clean?

Perhaps I am paranoid but this doesn't feel right and I think that we all become attuned to how our bikes are running and something here feels wrong....

I would rather go to a bike shop with some idea of what could be wrong than leave myself open to any type of wrong advice or diagnosis.

Any advice would be great.

[seth]

I'd say to check the teabag again to see if more crap has got in there .
Give the high pressure filter a good clean with carb cleaner.
Fit an inline filter to the low pressure side of the fuel pump to stop anything else getting to it.
If it's all looking clean then I'd say some of the crud has got as far as the injectors and they'll need looked at as there is a filter in each injector .
Anyone that services them should be able to service them for you.
There is a great place in the uk called www.injectorclean.co.uk that will service them for £60 plus your postage to them.
I'm not sure about your part of the world hopefully someone local can advice you.

It seams to be that if you've never checked the fuel pump filters by 50000miles they can give problems as in that many miles it only takes a bad batch of fuel once in a while to build up crap in the filters.
Good luck .

[lil4399]

I agree with Seth, I would also look at the clutch and side stand switches, less than perfect connections can cause a host of odd behaviour.

[ringfeder3]

I appreciate that advice. I mate here has suggested checking a throttle sensor. Any comments on that?

[seth]

It's worth a check do a search as there's a thread on how to test it and adjust it .
It's also worth checking the throttle cables for excess play.

[shanered6]

I agree with above ..... but i would also change the airfilter when i cleaned mine with air line it never ran right again till i changed it , and i did all off the above suggestions it was only after a new air filter i sorted it .

[Andre]

And wouldn't the use of premium fuel ensure that the injectors are clean?

No

When you cleaned the fuel filters, did you clean the tank? What did the crud in the filters look like?
A fuel flow test and a fuel pressure test will let you know the condition of the pump and filter.

Does the fuel pressure regulator sit firmly in its place? Did you do the mod to the pressure regulator clip?

Throttle bodies synchronized? TPS and STPS (throttle sensors) adjusted?

Vacuum leak?

Clutch sensor? Airfilter?

Are the electrical connectors ok? Clean ALL of them with contact spray.

Spark plugs ok? Wires and Coils ok?

The electrical problem you posted here http://gsx1400owners.org/forum/index.php?topic=3549.0;topicseen may also have something to do with it.

[Mick_J]

I had a very similar experience and changed the plugs, coils, air filter, swapped air sensors IAP and IT, checked and cleaned all other FI sensors, removed checked and cleaned all vacuum lines, stripped cleaned and wired up the fuel pump then ran several doses of injector cleaner through.  Last thing I did was to replace the IAP with a spare I got from Andre and bike now runs perfectly.  It seems to affect K7 bikes and can be very difficult/frustrating to track down, good luck.

[Andre]

Forgot that one

[grog]

Mr Ring, very strange it plays up on over run. also at idle is strange. just no pressure on much in those modes. maybe an air leak at manifold, try spraying around it, wd40 or similar while idling, any change ?    no vac hoses left off? block off pairs big hose to try also. does it still idle at 1100 exactly? after those, remove battery negative lead, short it to positive lead, will drain the whole computer memory, maybe for around a minute. re connect, turn key on without starting for another minute. start her up, see how you go. often that re set works on lots of cars/bikes. its just a re learn, same thing as re booting phone etc. hope ive helped. 

[ringfeder3]

Seems to idle at 1000rpm. Surging more apparent around the 2000rpm point.

[Hooli]

I had a very similar experience and changed the plugs, coils, air filter, swapped air sensors IAP and IT, checked and cleaned all other FI sensors, removed checked and cleaned all vacuum lines, stripped cleaned and wired up the fuel pump then ran several doses of injector cleaner through.  Last thing I did was to replace the IAP with a spare I got from Andre and bike now runs perfectly.  It seems to affect K7 bikes and can be very difficult/frustrating to track down, good luck.

That'd make sense as these bikes only use the Manifold Absolute Pressure readings at low throttle opens/low revs. Swap it with the pressure sensor on the RH side of the airbox & see if things change, they are the same part doing different jobs.

It does sound like balancing the throttles & then setting the TPS & SPS would help though.

[ringfeder3]

Update. There is no suzuki dealer here and funnily enough, the yamaha/suzuki/kawasaki dealer didn't have the diagnostic equipment to fit a suzuki. So, i tracked down a retired suzuki dealer who lived locally. He has sold all his computer equipment unfortunately but kindly offered to take a look...

This bloke said he'd start with the basics. He took it for a ride. Observed the symptoms and suggested we adjust the chain tension. So we did...test ride. No difference. Looked at a few other things. No diagnosis.

Spoke by 'phone to nearest Suzuki dealer. Said flush system with injector cleaner. Guaranteed that would fix it....nope.

Another mechanic said it had to be the fuel pump. Guaranteed that as well...

So today, put a new fuel pump in. Cleaned tank, fresh fuel. Guess what? Same problem.

I convinced this bloke to take it for a ride partly to assure myself i wasn't imagining things. He said he could feel it too.

So, like thr earlier Suzuki man, he adjusted the chain tension....it felt worse.! Great!

Anyway, we put the bike on the centre stand and ran it in first and you could feel the vibration from the chain through the handlebars....the same 'pulsing' sensation we thought was the motor!

Turns out that the chain and sprocket were original....after 50000 km.....

I'd be thinking we may have found the problem. What do people think?

I hope bloody so.....

[Mick_J]

Probably right, change them.

[seth]

That's a big mileage change them and it should improve .