85hp force violent jolt when running and no not hitting anything

[War Machine]

I have a 1985 85hp force bought it about two months ago. finnaly got a few problems solved now this. When i get the boat started and running it runs well then out of no where there is a violent jolt as if i hit something but i know this is not the case. The motor runs smooth then this jolt happens and still runs smoothe. I can't figure this one out.

 

[jerryjerry05]

Re: 85hp force violent jolt when running and no not hitting anything

In the lower unit it's possible the clutch dog is slipping on the forward gear when it's under a load.
It will cause a sudden jolt/jump.J

 

[War Machine]

Re: 85hp force violent jolt when running and no not hitting anything

ok so how do i go about fixing this problem? Or should i just let a pro do it for me?

 

[jerryjerry05]

Re: 85hp force violent jolt when running and no not hitting anything

It takes special tools to fix this.Let a qualified mechanic fix it.The trouble is they don't make force motors anymore.Therefore the people who have the tools are hard to find.
Bayliner dealers woud be a place to start then ask at the local Mercury dealer. Good luck,J

 

[Robert D]

Re: 85hp force violent jolt when running and no not hitting anything

I just experienced this on my Force 150. It was the lanyard connection. I duplicated it by turning the connection while cruising, and sure enough, it caused it. Easy fix. New safety switch. Every time I bumped it it caused it, so new switch going in soon. Meanwhile, I just disconnected it for today.

 

[john from md]

Re: 85hp force violent jolt when running and no not hitting anything

Robert D. may have given you your answer. I have seen bad ignition switches cut out momentarily and then the engine catch again. This can also be caused by loose connections.

Check all of your wire connections for security. These boats get beat up pretty good and things start to loosen up.

John

 

[Robert D]

Re: 85hp force violent jolt when running and no not hitting anything

I found that turning the clip on the lanyard switch was enough to cause momentary interuption to the ignition. Felt like a real jolt. Tested the switch on the bench last night.....yep, it's wore out. Simple fix. After seeing the results, I would expect the ignition switch going bad would have the same result. Really a wake up when that brief jolt hits

 

[War Machine]

Re: 85hp force violent jolt when running and no not hitting anything

Thanks for the responce guys i will look in to this and get back to ya'll.

 

[War Machine]

Re: 85hp force violent jolt when running and no not hitting anything

Checked it out i found the thermo switch was not conected and broke could this be a part of the problem or do i need to keep searching.

 

[john from md]

Re: 85hp force violent jolt when running and no not hitting anything

If you are talking about the overtemp switch, the only thing it does is set off the alarm when the engine temp comes up. It has nothing to do with starting the engine.

John

 

[War Machine]

Re: 85hp force violent jolt when running and no not hitting anything

Ok i just wanted to see if this could be part of the problem. Would you know where i could find a replacement for the thermo switch online?

 

[john from md]

Re: 85hp force violent jolt when running and no not hitting anything

Sometimes they come up on ebay but they haven't been made for some years.

John

 

[War Machine]

Re: 85hp force violent jolt when running and no not hitting anything

Question Well i've found a lower unit for my force.I have a model # 856x5L
The lower unit i'm trying to buy is a Model # 856x3L They are the same year same HP, But will the new lower fit?

 

[john from md]

Re: 85hp force violent jolt when running and no not hitting anything

Yes. The only difference is that the engine was made in 83 instead of 85.

John

 

[Knightgang]

Re: 85hp force violent jolt when running and no not hitting anything

I would continue troubleshooting the electrical components before I invested in another LU. Could be your ignition switch, or the kill switch, or a number of other items...

 

[War Machine]

Re: 85hp force violent jolt when running and no not hitting anything

Thanks for the answer John.The lower unit i'm buying is a ebay find for $91.00 Looks good, seller says it came off a motor that the upper was bad.

 

[jerryjerry05]

Re: 85hp force violent jolt when running and no not hitting anything

Is it the same length?? They were made in 3 sizes.Measure the transom at the very bottom of the V and to the top of the middle of the transom.That should give you an idea how long you need. They came in 25,20 and I think 18/or15inches.J

 

[Knightgang]

Re: 85hp force violent jolt when running and no not hitting anything

Is it the same length?? They were made in 3 sizes.Measure the transom at the very bottom of the V and to the top of the middle of the transom.That should give you an idea how long you need. They came in 25,20 and I think 18/or15inches.J

Jerry, the shaft length has nothing to do with the Lower Unit. It will bolt onto any midsection regardless of shaft length...

 

[War Machine]

Re: 85hp force violent jolt when running and no not hitting anything

Thanks for all the replies. The lower unit arrived i removed the old unit Had a little trouble stabbing the new $91.00 lower unit From Ebay. Tested it runs perfect not a Jolt In sight.Thanks to all you have been very helpful.>>>

 

[timdan94]

Re: 85hp force violent jolt when running and no not hitting anything

if you want to fix that old lower unit it is fairly easy if you have a good machine shop around or a friend that does that kind of work. All I did was take the prop shaft out of the lower unit. then I drove the pin that holds the clutch dog on out and then took the clutch dog and re-machined the flats on the dog. it works fine now. It took about 4 hrs to do