Misfiring FZS1000

[Trebus]

I probably know the answer already but thought work checking.

Do the HT leads push in or screw out of the coils? Or more likely moulded in and therefore non replaceable? 

FZS1000.

Cheers

[Falcon 269]

They screw in.

It's worth trimming 1cm off the lead to get back to fresh core if you have any ignition issues.

[Trebus]

Thanks Falcon.

Still got an intermittent misfire around 4k. 

You did the slip on Ivan’s in this bike when my Dad owned it in around 2010. I’ve pulled them recently and they were spotless but the o-rings had deteriorated, all changed with Viton now.

EXUP is good, TPS I’m reasonably sure is good, carbs are balanced, all wiring been through to eliminate bad connections, plug caps stripped and test out fine, plugs are good but put a set of old ones in and no change. 

I knew the leads could be trimmed back but they’re a bit short now so plan to replace them now I know they screw out of the coils.

[unfazed]

1998-1999 Carburettor type R1 have the same plug caps as the FZS1000. It is unlikely the caps would cause an intermittant misfire as a specific rpm, I have found that problematic caps will cuse regular misfires expically on start up. Did you check the connections of the Ignitor.
A faulty TPS can cause surging at revs around tthe 3000 to 5000 mark as if you were on and off the throttle lightly. Just uploaded file to downloads section. The fault has been mistaken for a misfire, by a few fellows I know with R1s

[Trebus]

Thanks Unfazed, guess we’ll need to wait for admin approval on the download as currently can’t see it. 

I’d somewhat suspected TPS but my continuity checks appeared to rule it out. Igniter connections, can’t quite remember so will check.

[unfazed]

Thanks Unfazed, guess we’ll need to wait for admin approval on the download as currently can’t see it. 

I’d somewhat suspected TPS but my continuity checks appeared to rule it out. Igniter connections, can’t quite remember so will check.

How did you do the continunity checks of the TPS? Did you do a rotation test on it?

The Tachometer error codes are not foolproof as they only react to three conditions  Disconnected, Short Circuit or Locked in position.

Ufortunately they fail due to wear which causes the TPS to disconnect and reconnect quickly internally at certain rotation, but the ignitor reacts by changing the timing suddenly thus causing the surging. The disconnection of the TPS tracks are to short for the Tachometer error codes to show.
Since your bike is Ivanised and if it is surging then it would be caused by a failing TPS.

[Trebus]

I did static and a rotation test, the latter on the bike.

The rotation test seemed to give a linear result but it’s not the easiest test doing it manually. As a consequence I’d pretty much ruled it out as a failure. 

Maybe I should get another one and give it a try.

[Trebus]

Had a short run last week down to MOT and bike was OK. 

Nevertheless I bit the bullet and ordered a Suzuki TPS. Looks as though the part number has been superseded and is now 13580-21F01. Got a very good price direct from Japan, Fowlers are on back order. Let’s see if it turns up and how it goes.

[unfazed]

My Suzuki TPS 13480-21F01 the superceded version arrived today (I ordered two as my Serow takes the same TPS as the FZS1000) and will be fitting the one to the 1000 tomorrow. I will photograph how I change the wires and how I test them.

[Trebus]

Thanks Unfazed.

My Fazer is MOT’d up, took it out for almost 100 miles and it’s running flawlessly! Problem will be back I’m sure. 

New TPS has been despatched.

[Trebus]

£46 delivered from Webike, Japan.

[unfazed]

£46 delivered from Webike, Japan.

I got the two Suzuki TPS sensors I ordered 2 weeks ago on Friday and mosified and fitted one yesterday. The other I will fit to the Serow later.

I Test the TPS on the bike with the Throttle and the pins of the TPS connected to a Meter on the Ohm scale with a little test cable I made up specifically for this purpose. (If meter is not auto ranging set it to the K Ohm scale)

The meter drops out around 1.9kOhms and returns again at 2.2kOhms on mine, but coud also happen higher up the range

You just need to swap the Black and blue wires in the connector. I have uploaded a pdf file on how to do it.

It would not attach the Mp4 file, I will try to upload it to the downloads section

[Trebus]

Issue has returned! Will be getting the new TPS wiring sorted and fitted this week. Thanks unfazed for the advice.

[Trebus]

Well TPS is now replaced and thought all good but after 15 miles the misfire returned. I went out at the weekend too, behaviour similar with a below 2k RPM problem but only after riding for 20 mins or so. 

So managed to do some tests while everything was warm and turns out I’ve got a high resistance plug cap. Happy I’ve found something although I’d gone through the coils / caps a few months ago and they checked out fine. Seems like it’s a heat related issue. 

Anyway I’ve cleaned up the caps, changed resistors as I had some old spares and hopefully will be some progess. Just got to get it back together and test when time allows.

[Trebus]

Update on this thread.

I think I’ve ended up with more than one fault contributing to this misfire.

High resistance plug cap was rectified but still misfiring.

Further investigation through the wiring and checking of some of the well known problem areas showed up an issue with the ignition switch. When in the ON position the resistance was fine but merely touching the key gave much higher resistance so clearly a problem. I decided to strip it down which wasn’t so hard, I’d had it off before so the anti-theft bolts were already replaced. To get into the switch there are 2 other anti-theft screws, I managed to remove with a small drill and easy out. They were not very tight. Replaced with cap screws.

Inside there was some tarnishing of the copper contacts, cleaned up and put back together showing perfect continuity now even with pressure on key.

Coils, pick up coil, tip over switch and other interlocks all checked out good / within spec.

Now need to test again but I believe vibrations when riding would replicate the pressure on the key which could lead to an intermittent issue. 

Appreciate the assistance from unfazed on various emails. 

I’ll update further once I’ve tested.

[unfazed]

Craig

Check my email to you on the 30/4/2025 it mentions the issue specifically. You can bypass the wires easily and it does not cause any issue. They are there for extra security. It is an extensinon of the Side stand circuit. If bypassed at the Ignition everything esle works perfectly. If you bypass them and it works perfectly which I have no doubt it will then the ignition switch is the source of the problem. This is common enough on all the Fazers 600 and 1000

[Trebus]

Thanks Pat, I went through your emails on things to check. I’m confident the ignition switch is now working as expected but will consider a bypass should it still present problems.

Im hoping it’s now fixed but probably later in the week before I can try it and needs a few miles before declaring either way.

[schlumpf]

An additional failure cause I've seen in the past:
The housing of one of the coils had a small crack. At certain RPMs the spark took the shortest way to ground to the nearby frame. Hard to find and to be best observed in the dark (tank removed).
Though my first bet would also be on bad contacts somewhere in the ignition switch cabling..

To eliminate all unknowns and for short testing periods you could connect the coils's positive directly to battery. (The coil's negative is switch to ground by the ECU to create the spark)

[Trebus]

Thanks Schlumpf. 

I was reading through your website again over the last few days, very helpful information.

I still have your fine multigauge on the bike too

[Gnasher]

Late to the party on this one. Often misfires are simple, as mentioned above a cracked coil casing will do it as will cracked plug/s or plug caps even a holed/split HT lead. Check for arching, ride the bike and get it up to temp, either in your darkened garage or out side at night, remove the tank, start the bike and slowly rise the revs look down every plug hole and all around the frame area above the cam covers. If it's arching you'll see it, had a fair bit of this in over the years, sadly after owners had spent a small fortune!