84 merc stumbles at WOT

[DJnKY]

Engine runs fine at 7/8 throttle but acts like it is fuel starved at wot. Back off just a small amount and it runs fine all day. Carbs where cleaned and fuel pumps rebuilt to correct previous problem where motor would not run above 50%. Also new fuel line and primer bulb installed. sn 64525xx

 

[DJnKY]

Re: 84 merc stumbles at WOT

Are there no ideas as to what my problem could be?

 

[CharlieB]

Re: 84 merc stumbles at WOT

Air sucking into the fuel system from a losee fitting can prevent the fuel pump from suppling adequate fuel for WOT operation.

An easy test is substitute a TEMPORARY clear hose for the fuel hose to the carb and watch while running to see if any air bubbles are passing thru it.

Be SURE to remove the clear hose when finished with repairs as clear hose is NOT APPROVED nor recommended for fuel.