F90 2004 4 Stroke, Idle ok, Stalls on accelerate

[Charkra]

I have a Yamaha 2004 4 Stroke 90hp motor that idles rough and when accelerating then cuts out entirely. I have read many posts, and they vary from clean fuel to cleaning carbs, etc. (Yes I left the engine alone for +6months without starting, so initially suspected the fuel to be bad) I have stripped and cleaned the 4 carbs with carb cleaner (They did have a sticky grunge in them initially), and checked the 2 larger jets, and the absolutely minuscule channels that appear to lead to the idle vents in the main chamber, and all are clean and allow fuel to pass through. I removed all the old fuel from the tank, flushed the fuel pipe to the filter and pump. I cleaned out the filter, not much in that, Cleaned out the pump, no noticeable grunge in there either. (did clean the carbs several times as initially I did not clean the smaller idle channels) . The carbs have no adjustments in them at all, the only adjustment I see are the linkages to sync all carbs together.
On many responds the comment clean the carbs comes up, I am wondering if there is something else on these carbs that I am missing, so if anyone knows something specific about these, please can you mention it here - I have removed them several times, so it is getting easier to do I do know that 2 of the carbs have a solenoid switch (I have no idea what this does - seems to link to 3 orifices in the carb and has a pin down the center one) and attachment to them, and there is a line between these 2 carbs to the other corresponding 2 (ie Carb 1 has solenoid and is linked to carb 2, Carb 3 has solenoid and is linked to carb 4). These solenoids do get warm whilst I am at idle speed, so assume they are doing something but not sure.

I have cleaned all plugs, and checked there is a spark on the 2 coils that are in place (coil 1 -cylinder1&4, Coil 2 - cylinder2&3) , did swap them around to see if any difference, but none. The fuel pump definitely is pumping fuel > 10psi (max my gague went), and the float chambers do appear to have fuel in them.

Any help or direction will be very much appreciated.

 

[Charkra]

Ok looks like no-one else has this problem , interesting....:grumpy: An additional bit of information that I discovered today was that on the engine where the "accelerator cable" (Control Linkage) joins to the lever mechanism to adjust the carbs, there is what appears to be some sort of device that advances the timing(Throttle Sensor) . I can rotate that clockwise , and the engine definitely idles much better , and I can get faster rpm's, but not yet enough to get it past the hesitation piece. This is linked to the vacuum advance too, so I am sure there must be something here that is worth looking at . Does this ring any bells ? I also had a friend of mine come across and he believes that the mixture is too rich, and causing it to stall, somaybe the butterflies are not open enough when I am getting to the "just past idls" stage. I am still open to any ideas if anyone has any, Thanks in appreciation

 

[Charkra]

Found the problem - http://yamahamc.partsandwarranty.com/SyndicateNav.cfm?NodeID=1488179&Page=1 - On 3 of the carbs it was blocked - I had only checked the holes across, but not the one hole through. The only reason i found that , was cleaning the 4th time, poking thin copper thread through each hole , and noticed on the one jet, there was a hole, but on the 3 others there was not.. Moral of the story - Check everything again. if not sure, follow logically the flow of where the jet is getting the fuel from. Once this was cleared - it started and ran perfectly. Lesson learnt, - Patience is something that you will learn .... eventually . As mentioned in my first post - I should read it and answer my own question (clean the carbs ... properly)

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