1989 Force 125 Motor jerking

[northendbob]

When I'm driving down the river every 15 seconds the motor felt like it was jerking, the whole boat jerked. Just this past week end the jerking feeling started to happen evey 5-8 seconds. What could be the problem. Top speed is only 27 mph.?

 

[tjello327]

Re: 1989 Force 125 Motor jerking

Check compression first, If good, be sure all cylinders have a strong spark. Sounds like intermittent spark. If spark is strong and stable, better start going over your fuel system. Check fuel tank for restrictions, check float bowls for dirt or water and move to the fuel pump. The motor "jerking" to me sounds like spark coming and going.

 

[Frank Acampora]

Re: 1989 Force 125 Motor jerking

If it was making a good loud thump when jerking, then the drive dogs in the lower unit are wearing. This will happen at full throttle but not at partial throttle. The more they wear, the faster the frequency of the Jerk and the lower the throttle setting at which it happens, until they will no longer stay engaged.

 

[tjello327]

Re: 1989 Force 125 Motor jerking

Sounds like my engine. Mine was a more severe condition. I think Frank is right. Not sure how the engine sound mechanicaly, but like Frank said, if the entire boat is jerking and the engine isnt missing a beat, must be the main drive, like the dogs and gears.

 

[northendbob]

Re: 1989 Force 125 Motor jerking

Thanks for the information, Is it a difficult repair or is it worth. What would be a ballpark repair for a rebuilt lower unit? If that is what it takes.

 

[tjello327]

Re: 1989 Force 125 Motor jerking

If all that needs done is the drive dogs and the gears to be machined back to square again, all you would need is new o-rings, a few seals and a new crush collar for the drive shaft bearing. I can do the drive dog and both gear repairs for around $200. The other parts should be replaced so you dont have any leaks. The cost of those parts are around $75. All the labor to disassemble and reassemble would have to be done by yourself or someone else. Its not that hard of a job unless you start changing bearings and races. If you do, you need special pinnion depth measuring plugs and the proper know how. If you dont need new bearing, the pinnion depth wont change so you should be o.k. as long as you use a new crush collar.