Bogging down - loss of power

[Jez]

My FZ6 is a bit poorly. Ever since it came back from a service 2 weeks ago it's been getting worse. I noticed on picking it up that the throttle response was very jerky, both on the gas and off. At the time one of the mechanics who rode it asked if it was restricted in any way, because it felt like it was being held back a bit. Well it's definitely not restricted.

What happens is that as I'm going along, steady on the gas, it will suddenly bog down like I've just hit the brakes. I'll give it more gas to compensate and it'll slowly pick up again, but will feel like it's being strangled. Then suddenly it'll pick up again. It's a weird feeling to give it some gas and actually have it slow down. This'll kick in even at steady revs, any speed, any gear. It seems to only be happening when cold or first 20 minutes or so of a ride - normal temp on gauge. No warning lights coming on. Bike starts no problem, steady idle which dips a bit as it warms up.

I wondered if it might be a bad tank of fuel, but am on my 4th tank now since I first noticed this. I filled it with 97 last time, but it was still doing it.

Ah yes, lights. Last night I got on it, started no problem, and I just tested the main beam briefly to see it worked. It did. It runs with one dipped beam on by default. I left the streetlights behind, got out into the countryside, put on the main beam and suddenly all the lights went off. Only the two little sidelights on, and tail light. My instructor would be proud - I did a U-Turn on a narrow A Road in almost pitch darkness and headed back to the streetlights. Left the bike in a side street and called my friend to come and pick me up.

This morning I collected the bike and rode it cautiously to the garage. Checked all the cables I could reach and all seem OK. Still no lights. It was doing the bogging down thing again - like a surge, but the opposite. Give it some gas and it slows down, or even if you're steady on the gas it'll do it at random, just for a few seconds, and then pick up again. The lights thing might be a coincidence, but I suspect the problem is fuelling - if I pull the clutch in while it's bogging down it'll freewheel just fine - and it might well be electrical in origin. Maybe on the bumpy roads of darkest Suffolk (literally) some wire is coming loose.

The bike is a fuel injected 2004 Yamaha FZ6 Fazer. Any suggestions appreciated.

 

[Humperdinkel]

Here's a thought , have you had the TPS changed ??? There was a worldwide recall for a TPS problem , may well be the cause but im guessing your spanner man would know about this if he is a Yamaha repairer....

 

[Jez]

He's not a dedicated Yamaha dealer as such - more of a general bike workshop.

Good suggestion - I'll email him to see if he knows about it.

 

[Humperdinkel]

He's not a dedicated Yamaha dealer as such - more of a general bike workshop.

Good suggestion - I'll email him to see if he knows about it.

No worries , that would be my guess though :thumbup: There are a few thread on here re the TPS

 

[Motogiro]

Here's a thought , have you had the TPS changed ??? There was a worldwide recall for a TPS problem , may well be the cause but im guessing your spanner man would know about this if he is a Yamaha repairer....

Good Call!:rockon:

 

[Jez]

Solved :thumbup:

The TPS was a good call, but we found something else quite interesting at the garage. After I'd lost all lights the other night I suspected an electrical issue. The garage found that the relay box under the seat behind that left side panel was rotten with corrosion. All the pins were green and crumbling. The mechanic gave it a nudge with the engine running and the bike immediately stalled. No wonder the lights went out.

So they cleaned it all up, rewired a few contacts, and gave it back to me. Went on a 3 hour test ride and it's just perfect. No bogging down, no drop in revs at all. I love my bike again

They did say that they expected to see more of this kind of problem. The FZ6 pins there are like little needles, very fragile, and in a damp climate like the UK moisture build up can corrode the contacts easily. So maybe that's one to watch out for.

I still need the TPS done at some point, but right now I'm just chuffed to bits to have my bike back and in good health again :rockon:

 

[Humperdinkel]

TPS was a worldwide recall a few years ago that was repaired for free as it should still be if you missed out , get on it mate its makes a world of difference :thumbup:.... Glad its been sorted though

 

[TownsendsFJR1300]

There was a post about 2 weeks ago about the fuel pump relay (same location) going bad, lots of corrosion inside a sealed relay, (left side under the pod). He was getting low voltage to the fuel pump...

I gather its probably the same relay.

 

[Jez]

Well a lot's happened since I started this thread. And things are still a bit uncertain.

The fuelling problem returned a couple of days after I got it back from the garage. Was out for an hour and a half and it was perfect, then coming back into town, surging then slowing way down like I was braking, then jerking and finally stalling on a roundabout. Quick restart and it was fine again.

After weeks of hassle with a Yamaha dealer on the other side of the country who ordered the TPS by mistake and then failed to send it on, I managed to get the local dealer in Norwich to fit a new TPS under the recall. The bike was first registered in 2003 so this one is long overdue.

Anyway, so far so good. The throttle is generally smoother now, and I've had none of that bogging down / being strangled thing that was making it such a nightmare. No stalling despite rush hour traffic. So fingers crossed this has finally solved it.

Oh yeah, they gave me a brand new Yamaha Diversion as a loan bike. But the FZ6 feels turbocharged in comparison

 

[TownsendsFJR1300]

Yes, the TPS affected slow speed performance for the most part, exactly what your experiancing, stalling hesitation at slow speeds, etc... You should be good to go now...