Accelerator Pump diaphragm damage !

6 replies to this topic
  • mcpga

Posted July 24, 2013 - 06:26 PM


This is my first 4-stroke and my first time cleaning a FCR carb. I downloaded a manual and decided to give it a try. My 03 WR450 started to run poorly and then would not even start. Here is what I found when removed the AP cover. What would have caused this to happen? Any carb cleaning helpful hints will be appreciated!image.jpg

Edited by mcpga, July 24, 2013 - 07:50 PM.

  • GuyGraham

Posted July 25, 2013 - 01:03 AM


I believe its the ethanol in your fuel that rots the rubber

  • mcpga

Posted July 25, 2013 - 04:10 AM


Wow! I knew it wasn't good but I had no idea ethanol would eat rubber like that.... Thank you!

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  • weantright

Posted July 25, 2013 - 04:25 AM


Race gas also does this. Remember to clean the AP nozzle with a wire from a wire brush/wheel or something like. Verify all jets are not plugged with the rubber.

  • Krannie McKranface

Posted July 25, 2013 - 04:56 AM



...oh, and neglect.


  • mcpga

Posted July 25, 2013 - 09:21 AM


Lol! Got it! I shall not neglect my carb ever again... Thanks for the link!

  • tcmII

Posted August 06, 2013 - 06:46 PM


Did you use carb cleaner in it?  Carb cleaner should never be used on rubber and some plastic items. I have seen the exact problem in your picture specifically from carb clean. You can clean rubber and plastic with brake clean.


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