85 HP Force outboard jerks intermittently at WOT (see video link, please help)

[swiggins]

This is my first post, I appreciate any help I can get. I have a 1989 85 HP Force outboard. It starts, idles, and runs great up to about 3/4 throttle. It starts to kick or jerk about every 3-4 seconds when running at WOT. Another issues is that it only runs at about 4,300 rpm's at WOT. see video http://www.youtube.com/watch?v=AxxBl-8bykI&feature=plcp

I just bought this motor used and put it on my bayliner a few days ago. All three cylinders have 118-120 compression and have new plugs. I am guessing that the high speed needle on carbs may be clogged, what do you guys think?

 

[Jiggz]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

It could be fuel related if you vouch that it runs perfect at 3/4 throttle. Have you tried squeezing the primer bulb to see if it makes a difference? If it does it could be fuel pump related or as simple as a clogged fuel filter (on top of the fuel pump) or a leaky fuel line (sucking in air). If the primer bulb doesn't make a difference you will have to clean the carbs and check the float settings.

 

[emoney]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Whew...I watched that video and I wouldn't want to be too far from home before I fixed that. Listen to Jiggz, he gives good advice. When was the last time the carbs were serviced?

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

It could be fuel related if you vouch that it runs perfect at 3/4 throttle. Have you tried squeezing the primer bulb to see if it makes a difference? If it does it could be fuel pump related or as simple as a clogged fuel filter (on top of the fuel pump) or a leaky fuel line (sucking in air). If the primer bulb doesn't make a difference you will have to clean the carbs and check the float settings.

Thanks Jiggs, I will try that and post results.

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Whew...I watched that video and I wouldn't want to be too far from home before I fixed that. Listen to Jiggz, he gives good advice. When was the last time the carbs were serviced?

The carbs where supposedly serviced just before last owner got it (about a year ago).

 

[foodfisher]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Imho, your sucking air.

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Sucking air? Do you mean a fuel line or gasket is leaking? Can you be more specific? Thanks

 

[timdan94]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

I had a 1985 85hp force that did the same thing as in that video, mine was the forward clutch dogs slipping. It only did it above 3/4 throttle. Fortunately my dad was a machinist so all we did was re-machined the flats back on the clutch dogs and reassembled. That took care of the problem and it only took about 4 hrs to do.

 

[foodfisher]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Sucking air? Do you mean a fuel line or gasket is leaking? Can you be more specific? Thanks

Yes, air leaking in somewhere along the fuel system. Rewatching the video, I like timdan94's observation also.

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Interesting. From reading descriptions of other people with clutch dog problems, this does seem like the same issue. I have a spare motor, would it be easier to just swap out the whole gear case and see if that fixes problem?

 

[timdan94]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Interesting. From reading descriptions of other people with clutch dog problems, this does seem like the same issue. I have a spare motor, would it be easier to just swap out the whole gear case and see if that fixes problem?

I would to see if it fixes it

 

[Jiggz]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Interesting. From reading descriptions of other people with clutch dog problems, this does seem like the same issue. I have a spare motor, would it be easier to just swap out the whole gear case and see if that fixes problem?

If it's an identical LU I do not see any reason why not if the problem is slipping clutch dogs. However, usually with slipping clutch dogs the jerks are not as constant in frequency although with fuel problem it could be the same. Personally, I would focus on the easy diagnosis first before the hard ones unless you know for sure the source of the problem. The problem could also be electrical cause by worn out insulation in the trigger system. But start off with the easy ones first.

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Took the boat out today. Squeezing the bulb didn't change anything. I looked over all of the fuel lines and they all seemed to be in good shape. No sediment in fuel filter. Is there a trick to finding air leaks in fuel system? I didn't fully clean the carbs but I checked the bowls and they had gritty sediment in them. I looked into swapping the gear cases but they have different drive shafts. What's next? Carb?

 

[hunter9999]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Sounds to me like a clutch dog based on the video,
Check the linkage I have had them come loose before.
My 125 was doing the same thing jerking every few second at WOT.
Talk to a friend and he said I didn't have to pull the lower unit to fix it.
So just took the prop and the anti corrosion plate and water seals and then the reverse gear.
Next step was I unhooked the linkage down at the lower unit and pulled the linkage up as far as it would go as to release the drive shaft at the front and waala the drive shaft pull right out.
Then I just ground the cogs on the clutch dog straight and put it all back with new seals and bam good as new.
But yes I would bet clutch dog for sure because it sounds just like mine did when kicking out.

Let Me know I will provide more info if needed

Hunter

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Thanks Hunter. I'll get back to you if I have more questions.

 

[jerryjerry05]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

The others have talked about the clutch dog and a easy fix is taking it out and turn it around.
But if you can clean up the edges.
As far as the gas problem.
Any fuel line,inline connectors?Remove them.
The seals inside go bad because of ethanol.
The tank vent could be partially clogged.
Clean the carbs and check the reeds while they are off.
Check the diaphram in the fuel pump while your fixing.It's only a $6 fix on that.

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

I cleaned the carbs and put in new gaskets. Took the boat out this morning and had the same problem. I guess I will look into the gear case next. I started pulling my spare gear case apart and got stuck after prop and corrosion plate. looks like I need a special puller tool to get next plate out. Is there a way to get it out without puller tool?

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Hunter,
When you ground to dogs, did you grind the top or sides to get it back to square?

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

The others have talked about the clutch dog and a easy fix is taking it out and turn it around.
But if you can clean up the edges.
As far as the gas problem.
Any fuel line,inline connectors?Remove them.
The seals inside go bad because of ethanol.
The tank vent could be partially clogged.
Clean the carbs and check the reeds while they are off.
Check the diaphram in the fuel pump while your fixing.It's only a $6 fix on that.

The diaphragm in the fuel pump did have a small hole in it and 2 carbs were leaking a little. Had both fixed and engine ran smoother than ever but still having jerk problem over 25 mph. I have it at a shop now, I will have him check clutch and vent tube.

 

[swiggins]

Re: 85 HP Force outboard jerks intermittently at WOT (see video link, please help)

Sounds to me like a clutch dog based on the video,
Check the linkage I have had them come loose before.
My 125 was doing the same thing jerking every few second at WOT.
Talk to a friend and he said I didn't have to pull the lower unit to fix it.
So just took the prop and the anti corrosion plate and water seals and then the reverse gear.
Next step was I unhooked the linkage down at the lower unit and pulled the linkage up as far as it would go as to release the drive shaft at the front and waala the drive shaft pull right out.
Then I just ground the cogs on the clutch dog straight and put it all back with new seals and bam good as new.
But yes I would bet clutch dog for sure because it sounds just like mine did when kicking out.

Let Me know I will provide more info if needed

Hunter

Hunter,
I need help! The prop and corrosion anode where no problem to remove. The problem is the next thing, the bearing spool, I can't get that thing out to save my life! I broke my puller trying to get it out, am I missing something?
Thanks
Shawn