86 Force 85hp Runs good out of the water. Bogs at full throttle in the water.

[MattysVip]

Hi all, I just bought an 86 Vip 16ft Fish n Ski. The previous owner Rebuilt the carbs. It was hard to start but once running on Muffs it ran pretty good. But when i got it in the water I could only go 3/4 throttle and slowly. Any further it starts to bog and lose power. I found the manual for the outboard online and i adjusted the throttle sync, Adjusted the idle mixture screws to factory. Seems slightly better but I still cannot go full throttle. Highest Mph on the gauge i reached was 25mph with a slight chop in the bay. Anything i am missing? I have been a car guy all my life working on/building cars so this is a new animal for me but i am very mechanical.

 

[tg3690]

Possible fuel starvation problem. I would check the fuel pump diaphragm since you just bought the boat or just replace it. Fuel lines, tank vent, filters, squeeze ball, etc. Fresh fuel at proper mixture. Basic fuel system maintenance.

 

[jerryjerry05]

Air screws affect the low speed operation, once past 1/4
throttle the main jet takes over.
Do a compression and spark check.
Inspect/compare the plugs for proper burn.
Check spark on all 3 cyl.
Does it backfire, stutter, miss?
Do the starting fluid test, spray SF around the intake
side and at the bases of the carbs and under the packs.
If this makes the motor run different? then it's sucking air
someplace.
Check the float level? You should have 3 brass floats, one
might be leaking? or set wrong.
The 3 carbs are connected with a bar that opens all 3 carbs
at the same time, make sure they open at the same time
when the throttle is opened?

 

[MattysVip]

Thank you Topgun, I will start there and just replace the diaphragm and check the rest.

 

[tg3690]

Thank you Topgun, I will start there and just replace the diaphragm and check the rest.

Good idea.....since the boat is new to you get the basics done, if that doesn't fix it, do ALL the things JerryJerry said in second post.

 

[MattysVip]

Good idea.....since the boat is new to you get the basics done, if that doesn't fix it, do ALL the things JerryJerry said in second post.

Will do, I just ordered the diaphragm kit.

 

[MattysVip]

Air screws affect the low speed operation, once past 1/4
throttle the main jet takes over.
Do a compression and spark check.
Inspect/compare the plugs for proper burn.
Check spark on all 3 cyl.
Does it backfire, stutter, miss?
Do the starting fluid test, spray SF around the intake
side and at the bases of the carbs and under the packs.
If this makes the motor run different? then it's sucking air
someplace.
Check the float level? You should have 3 brass floats, one
might be leaking? or set wrong.
The 3 carbs are connected with a bar that opens all 3 carbs
at the same time, make sure they open at the same time
when the throttle is opened?

Thank you for all the Tips/Info Jerry.
I will be doing these checks once the rain we have coming is over. Before i adjusted the idle mixture screws it did backfire a bit while trying to start. I have them at 1 turn out for now. I also noticed fuel would dump out of the #2 carb (Center) while starting with the engine cover off and the intake cover off. I don't remember which carbs but i noticed 2 have the same size jet and one has a different size jet. I am assuming it is for high speed for more fuel. I will order new carb gaskets so i can remove the carbs and check the float level even though i am assuming the guy that rebuilt them (Previous owner) already did this. I also already adjusted the bar for all three carbs and they are all opening the same.