Carburetor issue

[xxmartinxx]

Aq205a carb issue
Hi I have a fairline weekender 21 with aq205a & dp290 volvo-penta, the issue I have is my carburetor (quadrajet 4bbl 17088142, 0799 ) run really well in tick over pulls away ok but when I go full throttle it doesn't to anything the secondary valve s looks ok, max speed at the moment is 10&12 knotts at 1500revs I have recently serviced it, I did by the carburetor 2nd hand

 

[Caraway]

I don't know the carb you refer to, but as a general rule it sounds like a main jet problem. Cleaning it properly and blowing out using an air-line sounds like a good start.

 

[ChromeDome]

.. and be extremely cautious if tempted to poke anything moke solid than air though jets et al..

Repeatedly soaking it in Brake Cleaner, a little time to work and then compressed air.

Seals and gaskets plus parts looking in any way worn should be replaced (special attention to float and valve/needle).

Apparently a marinized Rochester device, repair kit from Sierra should be #18-7072 - like
Sierra International Sierra 18-7072 Carburetor Kit, White : Amazon.co.uk: Automotive