I know a lot of Yamahas are fuel injected.
Many of them for several years now...

So I am hoping for a tech or someone who really understands efi & ecu's.


What would cause an EFI machine to be gutless at low RPM?
Just a great big STALL queen taking off, going slow or technical?
Stalling with no warning?
Sudden without a bog or sign a stall is near... almost like an ignition cut?
Even after dropping a tooth in the front!

The only thing that seems to help at all is adding the aftermarket exhaust system and subtracting the airbox lid. Don't know if that's purely power increase related, or if it's "improved air/fuel ratio" related?


My FI light is not on indicating a stored code.
I've checked everything there is a test for except the special test items...
Coolant temp sensor, air temp sensor, and pressure temp sensor.


All I can find is the same thing I found that sent it to the shop to begin with... the crank sensor resistance does not ohm out in range... it's too low. Comes barely inside range if you test it while hot... dunno about that either...


It could be one of those sensors I can't test (but the shop checked them before) or even a faulty ECU.

But I suspect that it is the ECU reading a faulty signal from the crank sensor and incorrectly adjusting ignition timing and fuel.... or the crank sensor may fail to send a signal to the ECU at a certain RPM, which would cause an ignition cut.

Any input from you guys is greatly appreciated because I am unable to find a Kawi rider that has experienced this problem.

 

i would say if ur crank sencer didnt read right i would replace it also have you cheked ur fuel pressureor fuel tank vents? you need to pull plugs and see what it looks like if it in proved with mods it kinda sounds like its getting to much fuel or timing ....jmo...

 

I have the same sort of feeling about the crank sensor.
I had in mind to replace it myself out of pocket the very first time.

But then I found out the crank sensor and stator were a rather expensive assembly.
So I turned it over to the shop to be replaced under warranty.

I am going to have to make a second try at that.
Just trying to learn more and make sure I'm barking up the right tree.


Plug still looks on the rich side. Better than stock, but on the rich side.

Yeah, I think fuel or timing... but all that stuff is totally stock so something must be wrong.

 

X2 if this a 700 motor we are talking about (either Grizzly or a Raptor) there have been a very few that have had this issue and it turns out to be a Crank Sensor or a clogged fuel injector due to bad fuel. this particular problem Bad fuel usually comes from the bike sitting to long with fuel in the tank.

 

I know that was a LOT to read through in a way...
But no, it's actually my Kawi 450R.

Here's a quote with all the stuff cut out of the middle...


I figured I had a better chance of learning something by asking more people.
And Yamaha is more popular and has more EFI units.



As for the fuel side, I am very **** now about my fuel... became that way before I bought this bike. I don't let my fuel set in them, or cans. I even test for ethanol before it goes in.

Fuel injector is clean, but not hard at all to check again.

Fuel pump should be clean too.


So are you saying some 700 owners have had this and it turned out to be a crank sensor?

 

Yes MOST of the time and from most of the posts I have read on my bikes there have been a very few bikes that had issues like you are having at it has mainly been a Crank sensor or a Injector that has gone bad.

 

Ok... thanks very much... it helps to have information like that.

I don't want to be right, but maybe I'm crutching my way through this OK.

I'll call the shop tomorrow and make my quad a Dr's appointment.

I just hope they actually replace the part this time.

My dealers are Kawi/Yamaha shops... so they should be aware of this by now too.

 

Oh, and I be this has been extremely interesting on a Grizzly...

I bet it would stall as soon as shifted in gear, or as soon as the belt started to engage.


I know my 450R won't let me let the clutch out enough to feel it is engaging.
Not without stalling. Not even rolling downhill.