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Ask Noel Schembri Your Own Question
Noel Schembri
Noel Schembri, Marine Technician
Category: Boat
Satisfied Customers: 1954
Experience:  Advanced technical diploma
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I have a 1984 90 hp yamaha that will not stay running rough

Customer Question

i have a 1984 90 hp yamaha that will not stay running rough idle, will run if you hold the choke in
Submitted: 2 years ago.
Category: Boat
Customer: replied 2 years ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Noel Schembri replied 2 years ago.

Hello my name is ***** ***** I will assist you. The problem you have is that the carbs need a clean up and rebuilt as you have blocked jets that are not allowing the engine to idle. What you need to do is to remove the carbs and open their bowls. Then remove the needles, floats and all gaskets and soak the metal parts in carb cleaner for a couple of hours. Blow using compressed air making sure all the jets are open and clean. Reasselble everything back and it should run ok.

If you require further assistance let me know.


Customer: replied 2 years ago.
this was all done. that was the first thing we thought it could be. then we changed the cdi box (not it) then the stater (not it either) when
I unhooked the rev limiter wire it seemed to run better
Expert:  Noel Schembri replied 2 years ago.

when you press on the choke button you are applying more fuel to the engine thus it looks like there is still fuel starvation and that means that there is still a jet that is clocked. Also you would need to set the idle air screws to 1 1/2 turns out from fully in position on each carb.


Customer: replied 2 years ago.
ok, I have done this and there was no change
Expert:  Noel Schembri replied 2 years ago.

Ok at this stage start from the fuel tank, make sure that the pickup and vent are free, keep on checking the fuel line and bulb and any inline filters up till the engine. IF everything is free then the carbs need to go out againas there is still a blocked jet. You would need to get them cleaned via ultrasonic .


Customer: replied 2 years ago.
Nothing has worked you have any other suggestions