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2015 WR Started Missing at Low Throttle Openings, Now Barely Runs

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A few days back my 2015 WR suddenly started misfiring at 1/3 throttle or less.  It ran fine while accelerating with half throttle or more, but sputtered and misfired at lower throttle movements.  I went home and next day changed the gas.  It ran fine for about 10 minutes then started misfiring at low throttle openings again, not seeming to have any trouble with harder acceleration.  It slowly got worse at lower throttle openings.  Just because it was easy, the next day I put in the stock ECU just to rule out an possible ECU problem. Again it ran fine for about 10 minutes, then the same behaviour, but got worse much more quickly and was not running well at all when I got it home.  Next day I put in a new spark plug and it would not start.  I push started it and it would barely run sputtering terribly from the very start.

Any idea what might be going on?  From what I have read I suspect one of the FI sensors has gone bad, but I have no idea how to test this.  Am I better off just taking it to the shop?  Unfortunately I live in Iquitos, Peru and there are only two WRs here.  I have very little faith in thier ability to trouble shoot this, but not sure what choice I have.

I should add that they only sell 90 octane gas here, so I have been using octane boosters or about 15% benzene to get the octane up and avoid pre-detenation. The bike has less than 70 hours on it of easy to moderate riding, seldom wringing it out.

Edited by jimDavis

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Have you ever serviced the FI system? If not, that's your issue.  

Do you filter your fuel before it goes into the tank or use Ethanol treatment? That's why it happened.

The fuel pump clogs, the pump goes dry, and fails.  Often the pump will work fine for several minutes, until it gets hot.

The filter is removable (very tedious) and cleanable but preferrable replaced with an aftermarket version.

The nozzle gets ethanol corrosion on the tip, and starts to 'spit' instead of 'fog' the fuel.  

Even without Ethanol in the fuel, the nozzles do get contaminated and stop working properly. They can be easily cleaned with solvent, a rubber hose, a 9v battery, and compressed air.

 

 

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Kran is correct,  this is a fuel filter/pump issue.     If it was one of the sensors that failed the bike would flash a check engine light at you.

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Sound like my mates bike, fuel pump and his was nothing other than a clogged filter. Checked and cleaned the injector first etc, no difference. Even the Yamaha dealer was stumped. Fuel pump.

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Thanks for your input guys.  I took it to the local shop and will find out in the morning what they discovered.  If they are puzzled or the problem continues I will have them replace the fuel pump filter.

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1 hour ago, jimDavis said:

Thanks for your input guys.  I took it to the local shop and will find out in the morning what they discovered.  If they are puzzled or the problem continues I will have them replace the fuel pump filter.

Unfortunately, most dealers have no clue on how to troubleshoot bikes

You might have to take it to a local 'tuner' to find the issue.....

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Well, the local Yamaha dealer tried to tell me the problem was a low battery, that there were many sensors that needed the voltage of a fully charged battery.  I told them I had ridden the bike with a dead battery for a year without any problems, so that could not possibly be the problem.  It is actually easier to kick start than use the electric starter.  They gave me the run around, I questioned their competence and informed them three people said they had the exact same problem and it was a dirty fuel pump filter.  After about 20  minutes of back and forth I said I would pick it up the next day but was certain I would need to bring it back, again questioning their competence. After all, if the problem was what they claimed I could not have ridden the bike a year with a dead battery!!   Next day they said they did clean the filter in the fuel pump and cleaned the injectors.  Runs fine now.  Thanks again for all your input, I am sure without it this would have been a major ordeal trying to figure the problem out.

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On 8/31/2017 at 2:27 PM, jimDavis said:

Thanks for your input guys.  I took it to the local shop and will find out in the morning what they discovered.  If they are puzzled or the problem continues I will have them replace the fuel pump filter.

That was a mistake,   you should have just pulled the tank and then pump and looked at it yourself.

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Yeah maybe, but I've gotten older and a bit lazy (57) and would rather pay someone to do more than minor maintenance.  It worked out okay thanks to this forum.

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2 hours ago, jimDavis said:

Yeah maybe, but I've gotten older and a bit lazy (57) and would rather pay someone to do more than minor maintenance.  It worked out okay thanks to this forum.

That sounds backwards. Anything minor will take more time to take to the shop, than just doing it yourself.

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