Fuelling/Air odd problem help pls

I'll lay it out and try and remember everything I've done but I have an annoying problem with my 1150GSA Twin spark

A bit over a year ago, the left side went BANG (this may not be relevant, but it's the same side that the fuelling issue is on)

Neil sorted me out some bits from Ebay and bolted it all up.....working fine.

Bike hasn't been on road much since then (insurance/mot etc ) but went back on road properly in September......After one 200 mile ride, it started 'fluffing', similar symptoms to coil pack breaking down

Swapped coil packs, no difference....tried old ( known to be good ) pack, no difference.

Spark plugs ok, fuel pump noisy though.

Fitted new fuel pump (from an audi, 1/3rd price of BMW OEM)

No difference.

Changed filter (external anyway) No difference.

Messed around with TPS....no difference..reset to 3.5 and a bit

Took it to Neil again last week......we ummed and arred, changed plugs, tested TPS (absolutely bang on) and Throttle bodies (also bang on).

Left hand side plug fouled and wet, so changed.

Swapped fuel injector for another one (known to be working)....started up...BINGO!!! perfect!!

Rode home to Harwich, slight fluffing that got worse until last 15-20 miles, back to square one almost


Rode to Mavericks today to pick up a gaucho, initially ok, rapidly went back to fluffing and running on RHS only.

It WANTS to go, but its not.....you can feel it trying IYKWIM......
On rolling off throttle, there's a click....rolling on, the click becomes a sort of twitter that exactly matches the misfire....If there was a butterfly valve in the air flow and it was flapping all around, that's what it would sound like.
Tomorrow I plan to take the throttle body apart and make sure that there's no old screwdriver stuck in there or something ridiculous, but any other ideas welcomed.

I Need to get this thing sorted tomorrow or I will be buggered getting to Jamie's funeral on Tuesday

And yes, the throttle cables have been checked 79879786 times to make sure they're seated

Fanum said:

Swapped fuel injector for another one (known to be working)....started up...BINGO!!! perfect!!

Rode home to Harwich, slight fluffing that got worse until last 15-20 miles, back to square one almost

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Check for a broken wire right next to that injector plug, possible behind the sheathing.

You don't say if you changed the HT lead, I'd give that a go too as it might be breaking down and/or shorting to the head.

Darkness is a great way to find 'leaks' to the frame/engine, so get out there and annoy the Neighbours watching Sherlock

Timolgra said:

Check for a broken wire right next to that injector plug, possible behind the sheathing.

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Will do, TY

AndrewD said:

You don't say if you changed the HT lead, I'd give that a go too as it might be breaking down and/or shorting to the head.

Darkness is a great way to find 'leaks' to the frame/engine, so get out there and annoy the Neighbours watching Sherlock

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No sparks visible tonight, and the coil packs AND leads are nearly brand new.
I will swap the leads from side to side tomorrow though to rule it out

its a twin spark

I think you could dis-regard the spark issue as its a twin spark,unless the double ended coil under the tank and the pencil coil were fecking about at the same time.Possible but unlikely.
Have you checked the fuel delivery pressure to the injector?
I see youve changed the injector, so that rules that out.
Take off the injector supply pipe and point the pipe into a clean stainless steel dog bowl type of thing, and see what spits out when you turn the ignition on.
i wonder if the fuel regulator is blocked with shyte on one delivery pipe.
Also do you have a noid light?, its a 12 volt bulb type thing that flashes with the injector pulse when you stuff it into the injector plug, stuff it into the good side, and see how bright it flashes, then put it into the duff side, it should be of equal brightness.
The longer the injection pulse,ie giving it some welly, it will be a big flash, on crank it will flash dimly.
I reckon you have shyte in the delivery pipe or low pressure or a poor electrical connection to the injector, the noid light should show this up.Also any water in the fuel?
Any way i can help, just shout.

Nomad biker said:

I think you could dis-regard the spark issue as its a twin spark,unless the double ended coil under the tank and the pencil coil were fecking about at the same time.Possible but unlikely.

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Bill mentioned the LH plug was fouled, which one, or both?

Nomad biker said:

I reckon you have shyte in the delivery pipe or low pressure or a poor electrical connection to the injector, the noid light should show this up.Also any water in the fuel?
Any way i can help, just shout.

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Fairly sure no water in fuel (exterior 'see-through' fuel filter fitted, no meniscus of water visible under petrol)
No noid light, but I suspect your last line is most likely......it will run smoothly at coast, but bogs with load on, and it feels like a blockage too.
Will start on throttle body then start poking things up pipes after that tomorrow

Bill mentioned the LH plug was fouled, which one, or both?

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Tim Both left hand plugs were wet and sooty, so we changed them both and it made no difference.

I will dry and clean the plugs before re-trying after every option tried tomorrow, in case the wet plug hides the potential fix (that would be annoying!)

Check the main LH coil too.

I've been here, I think, and ended up replacing my throttle bodies after trying coil sticks, plugs, HES, balancing etc...

My engine used to try to die and I had to blip the throttles to keep it running when it should have been idling. Does your fluffyiness respond to some right hand action?

DitchWater said:

I've been here, I think, and ended up replacing my throttle bodies after trying coil sticks, plugs, HES, balancing etc...

My engine used to try to die and I had to blip the throttles to keep it running when it should have been idling. Does your fluffyiness respond to some right hand action?

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Yes.....I had to keep it revved with clutch in on the way back from Maverick's tonight to keep it running....even then, it conked a couple of times (most embarrassed....I'd just fitted a Goucho and at the traffic lights on a roundabout, juggling throttle and clutch to keep it running, I fekked up getting my right boot clear and dropped us in the road.....Fortunately Rosie saw the funny side of it and i only crushed some toes )

There's definitely a metallicy clinky noise going on in association with all of this, which is why i was going to start on the left hand TB tomorrow

Good luck sorting it Bill, hope to see you Tuesday

Cheers Tim....BTW, there's only one mail coil isn't there? (with dual output?)


I can swap the leads around, but it's not easy to test if it's worked because sitting idle it sounds/revs fine.....it's only when under load (ie riding) that the problem smacks you in the face like a rancid kipper

It's pissing me off now.

I'll be there if I can though....my loudest shirt is all ready

There is only one main coil: I think I've heard from our forum sage that the cylinders will fire with only one spark most of the time.

Now, I found that my problem was less noticeable when under power and warm (on the motorway) than at town speeds and the bike was cold. I still haven't been brave enough to try my self serviced TBs to see if I have learnt anything significant.

If there's loads of black gunk inside the TBs which block the airways and butterfly gap then you'll need to deal with that before you can learn anything about their condition.

Good Luck with your journey.

Fanum said:

A bit over a year ago, the left side went BANG (this may not be relevant, but it's the same side that the fuelling issue is on)

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It could be my memory but wasn't it running rough shortly BEFORE it went bang?

Related issue?

Have you checked for a spark at either or both plugs?

So, it could be an ignition fault on the LH side, or perhaps Ditchwater's right....or, you fixed it short term with a replacement injector then it gradually became worse again...Why?
Shit in the fuel system, the bike's been laid up a while maybe.

If the plugs are getting wet, then it is getting fuel but not being burnt off, pointing towards a spark problem.

Keith Chapman said:

If the plugs are getting wet, then it is getting fuel but not being burnt off, pointing towards a spark problem.

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Moist would be a more accurate description than wet.....they don't reek of fuel like they would if they had been flooded.....

On a thread over at ADVRider (i've been searching for answers all over the place ) Neil once wrote that he'd never had a main coil on a GS go 14 years....I will be stripping back the cable around the lead this morning to look for a cracked wire that may let it run ok on tickover but not under load, but it still 'feels' like fuel (or possibly air) that's wrong, IYSWIM


Will post back as I discover stuff, but thanks Keith

I'm gonna take a stab in the dark here

I had a Friends 1100RT that was pissing him off I did all that you have done (except stick coils before some muppet points out 1100s don't have them!)

Anyway in the end it was the HES wiring I may have been able to get away with the sensors but I changed them anyway

The wiring was all cracked and crazed and must have been shorting occasionally as the bike would just go dead and refuse to accelerate It was just like it went onto one cylinder

Maybe worth lifting off the black belt cover and seeing if the HES cable feels hard / stiff instead of supple

For what it's worth the 1100 didn't do any of the strange revcounter flicks or mess around as previously described The final decision on HES came after a couple of weekends phootering and I was checking plugs etc
The Ignition was switched on and I'd tried turning it over the spark was weak so I reached down to swop the plug for a new one and BANG it started sparking all on its own while I had the sparkplug/lead in my mitt!!!! Sparked for about 10 or 15 seconds it may have been more it may have been less but it still fucking hurt!

Hall sensors have cleared all the previous faults

Jaythro said:

Anyway in the end it was the HES wiring I may have been able to get away with the sensors but I changed them anyway

The wiring was all cracked and crazed and must have been shorting occasionally as the bike would just go dead and refuse to accelerate It was just like it went onto one cylinder

Maybe worth lifting off the black belt cover and seeing if the HES cable feel hard / stiff instead of supple

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You could be onto something there, C'mon Bill you're running out of time

Ran around block with fuel cap open to make sure no funny vacuum effects going on...no change

Removed injector, cleaned with thin cotton bud and petrol, no crap came out.....sealing rings ok, connections all bright metal on male and female...replaced.......ran nicely until went around block, then no change

Lifted tank....all fuel pipes look unkinked and not squashed.

Fuel filter had dirty (Grey tinted) petrol in it, but no sign of water still, so I replaced that with a brand new one and after an hour of ticking over/being run round the block many times, the fuel in the filter is clear and looks good.

Airbox clean and induction pipe has no dead mice in it
air filter clean, but replaced with an even cleaner one.
No change

Throttle body off.....Butterfly valve working fine, no discernible jiggle on the spindle, spring action good (ouch, nearly bit my frigging finger off actually!)

As i was doing that though, I noticed that the inner sheath of the throttle cable was damaged at the end, so I trimmed that right back and made sure action was smooth....no change to running

No stones or any grit or anything caught in throttle cam.

Hall sensor wiring lovely and fresh ( I believe a new HES was fitted as part of the renovation approx 2 yrs ago)

The only new info i can report is that the bike will idle nicely, but when set at a constant rpm above idle, it will sit there at (say) 2k rpm for 20 seconds or so, then start fluffing down and actually stall, with no movement of the throttle itself.

At higher ranges (4k) it will fluff down and then run very lumpily.

While I Was doing this at the 2k range, I was leaning over seat to watch the throttle cams and felt a distinct KNOCK come up through the bike....it coincided with the fluffing down as well......

Oil is spot on level.
The annoying thing is it WANTS to go....you can feel it trying, then it gets boggy and cant go.....it's the sort of feeling that at any time when riding, you're expecting a bang, a puff of smoke and some obstruction to clear through and away she goes, if you know what I mean

Thanks for the ideas guys...and Tim for calling with moral support

looks like it'll be back to Neil again.......but I'm not risking riding it to Manchester and back tomorrow

Incidentally, why the ferk do I have a second pulley on the alternator shaft?

It IS a pulley, clearly designed to take a V profiled belt, it's made of hard plastic and its ON TOP (ie in front ) of the pulley that actually drives the belt.....it seems totally superfluous to requirement and just makes it a bitch of a job to get the front cover off