90 HP Mercury Outboard High Speed Problems

brittsinvader

Recruit
Joined
May 24, 2004
Messages
2
Somebody please help!<br /><br />Boat: 16' Invader Bowrider<br />Motor: 90HP Mercury Outboard<br />Serial Number: 0B108156 Model Number: 1090716<br />This motor only has 200 hrs on it<br /><br />I was out on the boat running 3/4 throttle for about 10 minutes when the boat suddenly started feeling sluggish. (probably over heated due to failed water pump) I Immediately put her back on the trailer.<br /><br />Following is a list of everything done since then:<br /><br />Step 1. Complete new water pump (housing, impeller, gaskets, etc.) Definitly needed it, old impeller dry and hard as a rock.<br /><br />idled well ran OK at slow speeds but seemed to miss. no power to plane<br /><br />Step 2. New Plugs (factory Spec NGK-BUHW)<br /><br />Still missing and had no power to plane<br /><br />Step 3. Drained old fuel filled up with new fuel<br /><br />Still missing and had no power to plane<br /><br />Step 4. Checked plugs again. Plug six clean (not firing). Checked power with a meter and traced the problem to the switch box assembly. Replaced Switch box. All plugs now have spark. All Cylinders Firing.<br /><br />seemed to run much better. smoother idle. still no power. I can get it to plane when I'm alone in the boat but only capable of about half the speed. 18mph tops (I've had it up to 46 on glass) seems like its just not getting enough fuel.<br /><br />Step 5. Replaced all Fuel Filters (Inline Filter, Fuel Screen, Auto Blend Filter)<br /><br />No Change from step 4<br /><br />Step 6. Checked Compression all cylinders consistant. aprox. 130's<br /><br />Please Help. Any ideas on what to try next?
 

KCLOST

Commander
Joined
Jun 22, 2002
Messages
2,095
Re: 90 HP Mercury Outboard High Speed Problems

Based on your testing, it sounds like a carb problem. Based on your serial number, I would guess this is a mid to late 80's motor, so it could easily have some gum up in the carbs... I would do a complete carb rebuild... <br /><br />Get your manual and follow the directions, buy the rebuild kit for your engine. And go to work, then go fishing....<br /><br />Let us know....
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,680
Re: 90 HP Mercury Outboard High Speed Problems

check to make sure you wired the switch boxes in properly. As for the carbs, drain them and then refill them thru the air bleeds with engine tuner/cleaner. Doing this a few times might disolve the gum in the carbs.
 
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