Yamaha 90HP 4 stroke Rough idle and cuts out above 5000 RPMs - Help Needed

[msuspartan1994]

My 90HP EFI 4 stroke (2006) has a rough idle - until about 1,100 RPMs and will then operate normally through about 5,000 RPMs at which it will cut out as if it is starving for fuel. No issues seem are obvious between 2,000 and 4,500 RPMs. Trying to get my head around where to start in order to pin point the issue as from what I have been able to read it seems it could be several different issues. From other posts I have noted Idle control valve, gas primer ball, gas tank pick up through the VST High pressure filter. My first thought is to replace the fuel filter and low pressure fuel pump. Does it make sense that a weak fuel pump that runs off the cam could cause this at Low RPMs and not be able to keep up at above 5,000 RPMs? Any help with how to test various system parts and which ones should I look at first to avoid replacing unnecessary parts? Thank you in advance for any help here.

 

[DaveMoen]

Re: Yamaha 90HP 4 stroke Rough idle and cuts out above 5000 RPMs - Help Needed

I have a 2003 F90TLRB with the same symptoms. The spark plugs for cylinders 2 and 3 are not nearly as black as 1 and 4 are. I'm thinking that cleaning carbs 2 & 3 is probably the first thing to try. If you've already solved your problem, what was the cause?