Won't accelerate when hot.

7 replies to this topic
  • Punisher3

Posted November 02, 2015 - 05:01 PM


We have a 2012 450f monster. 61 hours on it. Once it has ran for about an hour, it will not accelerate when you nail the throttle. Bogs down with some back fire. Starts fine, idles well. It will accelerate slowly to about half throttle. When you nail it, it pukes. What I've done so far: new wire harness, new TPS sensor. Help!!! We love this bike (GNCC RACER). Need it to run the whole race.

  • Krannie McKranface

Posted November 02, 2015 - 05:17 PM


Fuel pump and or fuel pump filter


You need to filter your gas before it goes in the tank, and then replace the fuel pump filter per the manual spec (20 hours ?)

Edited by KRANNIE, November 02, 2015 - 05:17 PM.

  • grayracer513

Posted November 02, 2015 - 08:39 PM


Good one.


The fuel filter is not serviceable.  


You can get them apart, however, here's an older link: 




A more recent post from about a month back stated he was able to get the thing disassembled without damaging any of the parts. 


The symptoms are right for that.  Basically, the filter becomes a flow limiter, and the system can't deliver fuel any faster.  

  • Dexter42

Posted November 02, 2015 - 09:17 PM


You can buy a replacement filter or do as some have do and wash the current one with dawn but their cheap enough just replace it. I'm going to warn you it's a B!!!! Taking it apart, one black hose in particular, other than that it's not to bad. Take your time and crack open a beer!! It's going to be a while...

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  • Wiz636

Posted November 02, 2015 - 10:48 PM


Yep, what everybody else said. It becomes symptomatic when the fuel level gets low in the tank and therefore only the lower contaminated portion of the filter is trying to flow fuel. Just went through this on my '13. While the filter/pump assembly is not designed to be serviceable it turns out that if you are careful you can remove and clean (or replace) the filter.

  • grayracer513

Posted November 03, 2015 - 06:53 AM


Where is the replacement available?  Yamaha lists nothing other than the complete pump.

  • Dexter42

Posted November 03, 2015 - 11:04 AM


2010 yz450 bogs after 15 minutes http://www.thumperta...fter-15-minutes


They sell the replacement filters, I picked one up for $15 when I replied to this thread.

  • Punisher3

Posted November 08, 2015 - 06:09 AM


Thanks to everyone who replied. There are some very knowledgeable people on this thread. I am in the process of disassembly and cleaning. Thanks again.

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