1989 mercury 90hp not running good need help!

[luckymf7]

ok i have had the boat for like 2-3 years now and this problem is getting worse as time goes on. Its a 1989 mercury 90hp oil injection on a bass boat. The problem i have is that the boat starts up fine and idels good at launch but if u go to give it the gas to fast the motor dies but if u give it gas slow it speeds up fine and runs great at high to mid speeds. this makes it a pain in the *** to load the boat at the end of the day! PLZ any help would be nice i know how to work on motors and stuff just to not to keen on boats yet thanks Greg.

 

[luckymf7]

Re: 1989 mercury 90hp not running good need help!

can anyone help me with this? thanks.....Greg

 

[luckymf7]

Re: 1989 mercury 90hp not running good need help!

can anyone help me with this problem what screws to mess with ect.... thanks Greg

 

[MaggieRose]

Re: 1989 mercury 90hp not running good need help!

Have you checked to see if the main jets in your carbs are getting dirty? For a quick check, a screw on each side at the bottom of each carb should be pulled out. You should be able to see through from one side to the other, if not, your main jets are gummed up. Time to pull em and clean em.

 

[James R]

Re: 1989 mercury 90hp not running good need help!

Hi.
Sounds like dirty carbs. Gotta clean them.

 

[luckymf7]

Re: 1989 mercury 90hp not running good need help!

cool thanks guys i guess one weekend off of fishing to clean the carbs

 

[CharlieB]

Re: 1989 mercury 90hp not running good need help!

It never hurts to clean and adjust your carbs properly.

Pay particular attention to the idle circuit, too lean at idle and the motor will not accelerate and you end up babying the throttle until you are well past the idle stages then it runs fine, just as you have described.

Once your carbs are cleaned you need to set the idle mixture screws to your best idle speed while on the water in forward gear, then crack the throttle wide open in gear to check for any hesitation, if any hesitation then turn all idle screws out to richen the mixture, turn out just the width of the screwdriver slot and retest. it shouldn't take but a1/8th turn or so and your boat should jump.