2011 YZ450F Not starting after sitting for 6 months

6 replies to this topic
  • socalsavage

Posted December 24, 2014 - 03:10 PM


Ok so my son started racing last year so my bike has seen little action. I pulled it out this month and it will not start. Has spark . I took to local dealer and they found the same thing has spark. Told me to start with replacing fuel pump then injector if fuel pump doesn't solve it so I took the bike home. Fuel ump $400 after taxes expensive test. I was thinking that when I take it to a Yamaha dealer they would have the proper tools to diagnose my bike so I am 145 out of pocket and back to square one..

  • PsychoSane

Posted December 25, 2014 - 07:53 AM


That's crazy.  I can't believe they took your money and left you with such a poor diagnosis.


The service manual is part of the owners manual.   The manual describes the procedure for checking fuel pressure with a gauge and a specific adapter,  and for diagnosing the fuel injection system with their Yamaha F.I. Diagnostic tool.    I don't have one,   but I've read that it's also possible to see active trouble codes with the YZ tuner.


The fuel pressure is supposed to be 46.1 psi. The procedure for checking it is on page 6-3.    Checking it requires an adapter,  but I bet a resourceful person could work around that requirement.


There is a procedure for checking the internal resistance of the injector with a Ohm meter on page 7-37.


Also,  there is a lean angle sensor in the ECU so make sure the ECU is mounted in the stock location.


Do you smell fuel,  is the plug wet when it's pulled?


I'm new to my 2011,  having only owned it for a month or so.    I couldn't get the thing to start no matter what I did.    I could see a spark when I pulled the plug,  grounded it,  and kicked the bike over.   I could smell fuel from the exhaust,  and the plug was wet when I pulled it.    Still couldn't get it to start,  so I tried a new plug and it fired right up.    Another thing I've found is that the bike doesn't like to start when I kick it over as hard as I can.   What happens is that I was kicking it so hard that I was spinning the cam fast enough to activate the fly weight on the automatic compression release,   so I fouled the plug.    Probably not much help to you, but I thought that I'd mention it.









  • socalsavage

Posted December 25, 2014 - 09:27 AM


Thank you. I know that was why I took it to them was I figured they would have the pressure gauge to check the fuel but all they did was put 12 volts to the pump. It is very frustrating. I am going to have to buy a gauge and test it myself. Also will be doing the ohm test for injector.

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  • socalsavage

Posted December 25, 2014 - 11:42 AM


Ok so I took a battery and leads and tested the injector I can hear a distinctive click each time I put power to it. The weird thing is I plug the power back to the injector and kick the bike over and it starts for a second then dies. So I am assuming gas gets through the injector when I applied a jumper to the injector so does this mean fuel pump is not putting out enough pressure to run?

  • PsychoSane

Posted December 25, 2014 - 02:53 PM


You'll never know for sure what the pump is doing without a pressure gauge.  


EFI injectors typically need fairly high pressure to operate.


Just shooting ideas out there,  there is a thread around here wherein a TT member removes,  cleans, and reinstalls his fuel filter.   There are also low cost replacement pumps,  of which I have no experience with.




Hopefully,  GrayRacer will see your thread.   

Edited by PsychoSane, December 25, 2014 - 02:57 PM.

  • Dexter42

Posted January 07, 2015 - 10:57 AM


Any updates on this one?

  • Garett0439

Posted January 17, 2015 - 01:56 PM


Have someone hook a strap to your peg and pull you around the neighborhood in gear until it starts. Sometimes it just takes a little more than a kick can deliver. A few weeks ago I pulled a bike for what seemed like a mile before it finally started.

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