It sounds very much to me that it is running rich at the lower end which is why upping the CO was set lower than expected and why turning up the fuel mod makes it worse. It could be the injector. Could you also have a look and see what part number the ECU has printed on the side. These threads will help in identifying your ECU.

http://www.xt660.com/showthread.php?t=8546

http://www.xt660.com/showthread.php?t=519

ECU model
 

The model number is 5VK-8591A-00, 112100-1870, 12V TBDF08, P.

I've contacted Yamaha about the TPS and ECU recall, they said the TPS recall has already been carried out and the ECU is not affected-there was no recall for the ECU.

Thanks for your help mate.

Is there an easy way to clean the injector? Or should it be replaced?

Cheers

Matt

You could run a bottle of fuel injector/cleaner through the system ,leaving it to idle...redex or similar. I would run a whole bottle through the system with a small amount of fresh petrol.

I've run the bike for a while with the cleaner through in high concentration - it was idling fine so after an hour I took it for a ride. The problem spot had shifted to higher RPM, the lower RPM was fine.

I rode about 800m then the bike wouldn't run. I pulled over and gave it time to cool off or something as it wouldn't idle and any gas would cause it to cut out.

I managed to get it idling and just clutched it back home.

I started it up last night - idling is still difficult so will dump the fuel, inspect the filter while I'm at it. Hopefully with fresh gas it'll be good.

Update to come when I get a chance.

have you checked your plug?..what colour is it?..it is the original now your running?..

Update
 

I got to take the tank off today to check out the filter... I'm surprised it was working! The amount of sediment = about 1/3 cup... rust all over the place.

I've order a new pump with new filter from Alibaba - cheap!

I'll try post pics...

I'll check out the plug - it's the original back in there.


What can I do to clean and prevent rust or does it not really matter?

you can get a petrol tank sealent ..ebay should help. Personally id put some ball bearings/marbles inside with some petrol and aggitate the tank till you feel you got the loose stuff out and flush it out maybe use an airgun..carefull with your eyes tho.

AND keep your eye on the filter..not sure if there's a secondary filter on these..you could add an inline one though..belt and braces and all!

Thanks for the advice Nicrok, great ideas!

I was thinking of trying a product called evapo-rust. It's non corrosive so won't affect the paint, worth a shot!?

I'm gonna take a look for an inline filter and tank sealant...

Thanks mate

Do a forum search re in line filters...due to the fuel injection system i think Kev said that in line filters needed to be able to withstand 3 bar..but i cant remember..im just home after nasal surgery and general meds are still working.

Finally...!!!
 

Hey Guys,

Well I replaced the fuel pump and it still didn't work. My guess was it was a high flow fuel pump, I measured 54psi so I moved on from there and fitter the old one. I thoroughly cleaned the tank of rust/scale and cleaned the filter too as the kit I got had a filter too large for the housing. It was full of rust scale.

I ordered a new injector and waited about 2 months for delivery as they were out of stock.

I finally got to put it back together with the new injector, put in fresh fuel, a new denso plug and gave it a few cranks...

Finally! Sat there purring, did my Rev check and went for a ride. Perfect!

Well almost, it's a little snatchy in 1st and 2nd but I'm guessing that's the chain tension.

Mystery solved!

I don't see any real recommendations for installing an inline filter so I'm just going to keep it topped up with gas to keep the rust at bay.

Thanks for your help guys,

Matt