rough between 3600 and 3900 rpm

[max2000here]

ok heres the problem, the engin starts great, it idles around 700rpm and runs nice and smooth until 3600rpm,,, from 3600-3900 the motor studders until i get to 4000 rpm from there to 4700 it runs nice and smooth, any suggestions would be great thanks, btw i replaced both fuel pumps and also the fuel lines, i ran sea foam through the carbs and the spark plugs are new thanks alot scott

[jb123]

and...what kind of motor are you referring to?

[max2000here]

its a 1994 yamaha 150 saltwater series with 240 hours on the motor

[jb123]

i would breakdown clean/soak carbs and clean each orifice.replace all worn aluminum washers and main jet o-rings.

[max2000here]

hopefully this helps some, i cleaned all 3 carbs and it took care of the problem, the boat runs great thanks

goodnews!!

[cyrillefrenchy]

hi jb123
what do you call "aluminium washers"?
are they in the carbs?
frenchy

[jb123]

yes..on the main jets and drain screws...they corrode quite easily.