It feels like someone is flicking the engine kill

[helmetvonthrob]

This started about 10 days ago.


I was splitting lanes on the M25 and needed to do a 2 lane split so found a gap and shut the throttle whereupon the forks dived and it felt like the engine had died.  I got into lane, made some space then shut the throttle, pulled in the clutch and it stalled.  I let the clutch out and it re-started.  It had a bit of an on off feel to the throttle response.


So I got home and tilted the tank, checked obvious pipes off, no joy.  I opened the airbox and it does need a new air filter (I've got one on order).


Put the bike in last week to a local independent for the throttle bodies to be balanced, plugs and an MOT.  It's come back with less of a flat spot


I went to deepest Kent yesterday and coming back I got the same effect.  Sat in the contraflow on the M3, I got to the point where I could just make the bike skip a beat at a certain throttle opening, just like an occasional misfire.  Pulled the clutch in as I approached my parking spot and the engine cut out again.
I guess this could be caused by heat build up as I was travelling at "ahem" mph round the M25 before trundling through the roadworks @ 50mph for 16 miles.


I am thinking from what I generally know about cars that it could be a faulty throttle pot but I don't know enough about the system to say for sure.


Anyone?

[Boris]

It maybe your Throttle position sensor breaking down. This usually happens when you either slow right down or come to a stop and the engine dies on you. Which if it does and catches you out, you can end up on the floor . Unfortunately unlike the TPS on a FZS 600 which is easy to get at and replace. Those on an FZ6 require the tank, airbox and injector bodies removed to access the little blighter. Which then has to be set up with a voltmeter. Price for a new one is around the £90.00 mark. Don't buy second hand, it ain't worth it.

Hope this helps.

[helmetvonthrob]

So I'm guessing it's £90 for the part and £200 to fit it!


IS there a way to test it?

[Boris]

There is and it's shown in the FZ6 Haynes manual, but still involves lifting the tank and I can't remember if the airbox has to taken out as well. I know when I had the problem on my bike there were several FZ6 websites that also covered this is issue. Try typing "Yamaha FZ6 sensor problems" on google and see where it takes you.

I believe there were issues with 04 TPS units which was addressed and improved on 06 models onwards. At the time I was rebuilding my bike I fitted 06 throttle bodies as the originals were pretty naff. The 06 bodies came with a TPS unit already fitted. Though I still had my local dealer set them up and the TPS.

Since then my bikes been brill.

Unfortunately when issues like this occur it's a process of elimination.

[Grahamm]

There is and it's shown in the FZ6 Haynes manual, but still involves lifting the tank and I can't remember if the airbox has to taken out as well.

I've just had a look at the Haynes manual and, yes, you need to take out the air filter housing too.

Once you've done that you need to disconnect the sensor sub loom wiring connector, then you can clip multimeter leads to the terminals and see if the resistance suddenly changes as you twist the throttle.

[helmetvonthrob]

There is and it's shown in the FZ6 Haynes manual, but still involves lifting the tank and I can't remember if the airbox has to taken out as well.

I've just had a look at the Haynes manual and, yes, you need to take out the air filter housing too.

Once you've done that you need to disconnect the sensor sub loom wiring connector, then you can clip multimeter leads to the terminals and see if the resistance suddenly changes as you twist the throttle.

IS there an ohm range as the throttle opens?  I guess I am looking for it being a smooth increase (or decrease).

[Grahamm]

IS there an ohm range as the throttle opens?  I guess I am looking for it being a smooth increase (or decrease).

According to Haynes:

Resistance max: 4 to 6 K ohms @20 degrees C
Resistance range (for position adjustment): 3.5 (or less) to 6.5 K ohms
Output voltage (at idle): 0.63 to 0.73 Volts

[sarelt]

Hi there,


I had a similar experience and it turned out to be the killswitch itself. The contacts start wearing of and then when you hit the slightest bump in the road it loses contact and cuts the engine. It may be worth checking that because it a lot less work involved.

[helmetvonthrob]

Hi there,


I had a similar experience and it turned out to be the killswitch itself. The contacts start wearing of and then when you hit the slightest bump in the road it loses contact and cuts the engine. It may be worth checking that because it a lot less work involved.

[/size]The bike is doing it at 50mph on as flat a road as we get in the UK nowadays.[size=78%]

[/size]I put the bike in diag. mode and the throttle value is linear and within tolerance when it is operated (cold) haven't tried it engine hot.[size=78%]

[/size]So I checked with Yamaha UK and apparently my 2005 Faxrt HASN'T been part of the recall programme so it's going in in 10 days time to West London Yamaha to have the TPS changed FOC![size=78%]