Accelerator Pump diaphragm damage !

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

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

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

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.

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

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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