1988 Force 85hp

[tallboy]

I have a 1988 85hp Force and have had some issues with the engine running very rough at mid range. It will run fine at idle and WOT. I removed and cleaned the carbs but that made no difference. I checked the sync of the carbs and they all move at the same time. When i disassembled the carbs there was a spring between the bowl plug and main jet what is that spring for? Now the last time i used it it will idle fine but will not throttle up much past mid range. Any ideas where to start.

 

[sidenberg]

Re: 1988 Force 85hp

The roughness at midrange may be a result of improper idle mixture screw setting. The other problem of not being able to throttle up past midrange may also be a result of the idle mixture screw setting or it could be your throttle cam is not properly set against the roller. That is all part of the link and sync procedure.

 

[tallboy]

Re: 1988 Force 85hp

You mention the link and sync procedure. I have a tech manual for this engine but it is kind of unclear on that process. Maybe you can enlighten me on the correct procedure. When adjusting the air screws turn them in until engine speed changes then back out until engine runs smooth?

 

[sidenberg]

Re: 1988 Force 85hp

If you own a Force you need to have a manual. Clymers is probably the better one and can be purchased easily on the internet. For a 1988 85 HP Clymers says start at 1-1/4 turns out from lightly seated. Then with engine warmed up at idle speed turn mixture screw counter clockwise in 1/8 turn increments pausing at least 10 seconds until idle becomes rough due to over rich mixture. Then turn screw clockwise using same procedure until engine misfires due to over lean mixture. Then position screw at midpoint between 2 points. Again you need to have a manual. It is a great read!

 

[jerryjerry05]

Re: 1988 Force 85hp

Set air screw at 1 and 1/8 turn out and leave it.
Midrange and up,could be a bad diaphram or valve in the pump or possible a bent/broken reed.
The spring must be there,it holds the main jet in place.
Have you done a compression test?Compression needs to be even or real close on all threecylinders. J

 

[tallboy]

Re: 1988 Force 85hp

Thanks for the info will try those adjustments.

 

[john from md]

Re: 1988 Force 85hp

Are you also getting more than the usual smoking and poor fuel economy? If so, your diaphram is leaking. This engine will run fine at the extreames (with the exception of the smoke and fuel burn) but will be rough at midrange with a diaphram that has a hole in it. Don't forget to replace the gasket also, $5 should cover parts.

John

 

[my1stboat1]

Re: 1988 Force 85hp

you know someone broke said something about the spring in the main jet... When i took my carbs apart 2 weeks ago for a thorough cleaning the top carb didnt have that spring but the other 2 did ... Why is that... I was pondering the thought that someone lefted it out previously, Im the new owner of this boat and its been sitting a long time so i took everything apart to clean... Thing is i had the boat in the water last week and even with that spring not in the top carburetor it ran like a top... So again im wondering should i get another spring and put it in the top carb as well as the other 2 ..



thanks guys

 

[john from md]

Re: 1988 Force 85hp

The spring is to keep the float from bouncing. When it starts bouncing, you tend to get an overly rich mixture.

John

 

[my1stboat1]

Re: 1988 Force 85hp

john that spring isnt the spring were referring too... theres a spring that sits over the main jet and then the bowl bolt keeps it pushed in

 

[john from md]

Re: 1988 Force 85hp

That spring is needed to keep the main nozzle in place. The main nozzle is pressed intoits well and the spring sits between it and the main jet or on side jet carbs, the plug that holds the float bowl on.

John