Re: Please help on......... 1998 90 HP Mercury
Hi Ezt13,<br /><br />I have a 2000 model 90hp, my experience with that motor is that the mixture settings on the carbs are very sensitive. If the motor has been adjusted or setup while in a test tank it is almost aways set too lean to idle properly when in the water. Do as suggested by Poorboy and then carefully check your settings on the mixture screws, mine runs best at approx 1 3/8 turns out from lightly seated, even 1/8 of a turn has a big effect on running, it will go from an intermittent lean sneeze to a perfectly smooth steady idle with these changes. <br /><br />You can try just turning out the screws an 1/8 of a turn at a time just to see if there are any improvements. The clearance between the throttle cam and roller is also critical for good performance, but has no effect at idle or very low speed (up to approx 1200 rpm), this clearance varies between different model years and is done using the throttle stop adjusting screw to align marks on cam and roller then adjust clearance to spec. <br /><br />Once setup properly I find the motor runs very well with good strong performance right through it's rpm range.<br /><br />Bob
