Rough running 2.5k to 3.5k

[Hubb96]

Hi all, 
New to the forum and not long had my 2004 Fazer 1000 but in need of some advice!

To give some perspective the bike runs fine high revs and the way through with smooth throttle, however it has a bit of a lumpy idle and a misfire at 2.5k to around 3.5k, this is very apparent in the 30’s which is making them hard work with the jerkiness. 
I have temp checked the headers and cyclinder 1 seems to not be getting as hot but only be around 40 degrees compared to the rest so suspect this is the one missing. 

I have changed the coils to brand new ones, changed the spark plugs round to test if one is faulty (same result every time) changed the plug caps round from the full running cylinders to no avail. 
Cleaned up all earth connections for the coils and the battery strap. 

I have had the carbs done at my local bit shop with all pilots and o rings sorted, diaphragms also done and cleaned out and then balanced so it runs lovely higher up. 

Air filter all good and fuel pump is priming as it should. Set the TPS many times and the clock test says it’s ok. 
However this is where I need some help - I have checked the ohms rating on the TPS and when I test the black and blue wires it reads 5.5k ohms. 
Then when I check the yellow and blue wire whilst slowly opening the throttle it runs from 0.6 ohm up to a max of 6.9k ohms, but this is momentary, whilst opening the throttle slowly it doesn’t seem to go up progressively, instead it jumps up and down from the lowest reading in between all of them, spiking it. 
The spiking seems to happen when I have the throttle a tiny amount open (ie how it would be when in a 30 holding constant speed at those rpms)

I’m not sure if this is the reason it’s jumping when at constant throttle or not but wondered if anyone could lend some advice? 

It might also be worth mentioning my bike doesn’t have the exup fitted, this lowers low down grunt but I can’t imagine it’s causing the misfire as described! 

Many thanks in advance chaps!

[unfazed]

Common enough issue and the only way to fix it is a new TPS. The TPS is a physical unit not electronic and it wears. When the ohms jump around like you say it effects the ignition timing.
The Yamaha branded TPS is ridiculously expensive, but the
Tourmax TPS-107 and Suzuki  13580-26F00 which has been superceded by 13580-26F01 are direct replacement for the Yamaha 4XY-85885-00
and the Tourmax TPS-113 and Suzuki 13580-42F00 will also work, but need 2 wires reversed in the plug (Usually Black and Blue)as they operate in the opposite direction to the FZS1000.

The FZS1000 TPS is not spring loaded like the FZS600 which also have two different ones which will fit but only one will work as they cannot be modified

[Hubb96]

Hi Falcon,
Thanks for all the info on what models I can purchase instead of the £200 unit from Yamaha.
I thought I’d double check today and test again, this time from cold the unit was all within specified range. With no jumping around, so I thought I’d then get it up to operating temp and try again.
The readings then simply weren’t there, I could not get a resistance reading for either method and it seems completely dead. I’m not a wizard in any way with this and wondered if that is a way of saying that that the TPS is effectively dead at operating temp?
As like I said, when it was stone cold it worked!

Tearing my hair out with this a bit as I don’t want to sink money into unnecessary parts!
Thanks for replying as quick as you did!

---

Now after about 10 mins of cooling down the resistance readings are back to normal… I’m confused!

[Gaz66]

Hi Hubb:

Welcome.

Re: Ohms testing a carb'd bikes TPS.
From what you state in your post, you're actually doing the test wrong.
Test procedure below:

Ohms testing any electrical component is to determine if it's outside of manufactures specs ie) Open circuit / high resistance.
All components under Ohms test must be unplugged.

Ignition pickup coil = (248 ~ 372ohms) unplugged, test across 2 pin connector behind right side panel near fuel pump.

TPS = (4~6Kohms) unplugged.

Ohms test is a static test, you gain nothing by rotating a tps during an Ohms test.
Set meter on 20K Ohms, touch leads together for a few seconds, what does display read?
Any resistance displayed is in the meter/leads & must be deducted from components tested value.
Connect multi-meter (Black/Negative) test lead to TPS Blue wire & meters (Red/Positive) test lead to TPS Yellow.
Display should read (4~6Kohms), if in spec, continue to DCV test TPS, if out of spec, replace TPS.

Voltage Test TPS:
Since TPS is a basic rotating 3 wire potentiometer it needs volt testing in motion to verify a fault.

Fully charge battery before any Volt testing.
Cold test first, then run motor up to temp, retest & compare values.
Connect TPS back up to bikes loom.
Set meter to DCV.
Touch meter leads together for a few seconds to zero meter.
Avoid touching meter lead ends, some meters pick up body voltage.

Connect meter (Black/Negative) lead to battery Negative.
back probe at 3 pin connector with TPS plugged into loom).
Turn ignition "ON".
Back probe TPS plug on Blue & Yellow wires, one of these should be a 5v reference, use the other wire that is the signal wire to test TPS.
Throttle closed, what does meter display = ? DCV, should be around 0.2v ~ 0.5v
Slowly open throttle up to full throttle, display voltage should increase, any sudden drops or jumps, TPS is faulty, it's usually dirt ingress up the shaft that causes a TPS to play up.
I use a small Ultrasonic cleaner for jewellery, ideal for sensors & injectors, use stainless lockwire to suspend TPS with shaft end upwards, often get a good amount of crap out of em, sometimes this sorts em, sometimes not, suck it n see deal.

Hope the above helps?

[Hubb96]

Hi Gaz,

Thanks for all the info! Having tested now I am unsure as to what the culprit of my dropping idle and hesitation is.
The ignition pickup tested at 320ohms so all good there.
Following all the instructions the ohms test was 4.8k cold and warm.
The volts is 0.68 with the throttle closed (which is higher then the max 0.5v you specified) and then runs smoothly up to 3.9v without and huge jumps or losses on the way to full throttle and back to closed.

Does the 0.68v mean the sensor needs attention or would this not cause the issue? As spiking isn’t happening and so I’m inclined to think my issue may be elsewhere?

Thanks for the reply, gremlins like this aren’t major but makes riding the bike less enjoyable when it isn’t quite how it should be!