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1988 Force 125 surging at crusing speed

ruby3068

New member
Hi everyone, its the first year with this motor on my boat and its been running great, however the only issue I'm having now is that if the motor is at half to 3/4 throttle it surges in speed. Full throttle is fine. So when I'm at crusing speed if I turn sharp the motor bogs down to the point I have to increase the throttle, as well if I trim up the motor picks up speed drasticly. The other related problem is when I accelerate or de-accelerate its a drastic jump or loss of speed, its never smooth which is really annoying. So I was kind of leaning toward timing, but any other ideas would be greatly appreciated to sorting out this throttle issue. Thanks Dennis
 
Welcome.
Don't touch the timing.
It doesn't change unless YOU change it.
Or a connector is broken something like that.

Surging is usually a fuel related problem.
It could be: dirt in the carb, bad inline connectors.I throw them right in the trash an replace with OMC or Yam. If it's needed.
Now back to the other causes: reeds in the recirc system, reeds, bad hoses, bad fuel pump.
Linkage out of whack.
Bad squeezie, something in the tank that's moving and blocking the pickup.
 
Welcome.
Don't touch the timing.
It doesn't change unless YOU change it.
Or a connector is broken something like that.

Surging is usually a fuel related problem.
It could be: dirt in the carb, bad inline connectors.I throw them right in the trash an replace with OMC or Yam. If it's needed.
Now back to the other causes: reeds in the recirc system, reeds, bad hoses, bad fuel pump.
Linkage out of whack.
Bad squeezie, something in the tank that's moving and blocking the pickup.

okay I will stay away from the timing, carbs sound like a good idea to start, so I will give them a good cleaning. Bad inline connectors ? do you mean fuel hose clamps? Not sure what you mean by reeds in the recirc system. I will replace the fuel pump since theres no way to tell. Not sure about the linkage, never touched it and cant really see how that would cause surging
 
If the linkage got out of whack.
One carb feeding more/ less than the other one.
The clamps holding the hose on a coupler or fitting could be loose and allowing air into the system.
Compression test?
Fuel pump, diaphragm, hole.
On the stbd. side of the block. There are 2 parts that look like dog bones on end.
The bottom of each has a reed valve that can get blocked and can cause surging.
Look up the parts diagram. Cylinder Drain Cover. It has a reed and screen at the bottom of each dog bone.
Could be carboned up and possibly cause the problem.
If it's carboned at all the power head needs to be decarbed and cleaned.

I use Mercury's Powertune or OMC's Engine Tuner Follow directions. Seafoam doesn't work on heavy carbon.
When the carbs are off, check the reeds for bent or broken reeds.

Post some pics of the dog bones.
 
Thanks I will look into these dog bone things your talking about and check reed valve and screens for plug up and carbon. Compression good on motor as I checked it and set timing at beginning of spring. I will check hoses and linkage too. let you know what I find thanks
 
Compression can change from 1 hour to another.
I have twin 88/85hp Forces.
If one of my motors coughs, bucks , misses or anything, I do a compression test.
It takes (me)40plus hours to do a rebuild the right way and I don't want to do one in the middle of summer.
 
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