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1986 Force 125hp has stumped two mechanics

M

Msutphin

Guest
" Problem began and acted just

" Problem began and acted just like a power pack went out. I replaced both and problem was still present (will start and run up to 2500rpm then shuts down). 1st mechanic started at fuel tank replacing all lines, filters, rebuilding Carbs. Compression check showed almost new readings. Kept boat 4 month trying all he knew and no fix. I brought boat home and tore it down to th powerhead, new gaskets everywhere, could find no cracks or indications of leaks, new wiring now, carbs rebuild second time, etc. Still no fix. Second mechanic concentrated on electrical including regrounding everything. He gave up after 3 months. Getting plenty of fuel to carbs, pumping bulb doen not help. Currently it starts and runs great up to 2500prm but try to go over the 2500rpm and it dies just as it is starving for fuel. Any ideas? "
 
" The Force engine is not my l

" The Force engine is not my line of expertise, however if this problem existed with an OMC product, I would do the following.

Remove the spark plugs, rig up a spark tester whereas you can set a 7/16" gap. Turn the key to the ON position. Crank the engine to obsevre the spark which should jump that gap with a very strong blue lightning like flame.... a real strong wide snap!

While cranking the engine, slowly increase the throttle so that the timer base, distributor, magneto, whatever that engine has, moves from its full retard position throughout its full range to the full spark advance position.

If the spark ceases to exist at some point in that movement, you could assume that there's a faulty wire (broken, make/break condition) which is associated with that movement. Or, at any rate, you'll know in which area the problem exists (ignition).

If, on the other hand, the spark is steady and strong throughout that movement range, you could assume that the problem is with the fuel supply and frankly.... the problem that you describe is usually associated with fouled or improperly adjusted carburetors.

If the compression is okay, no problem with overheating, no water entering the cylinders for any reason, etc.... that leaves the ignition and fuel system. It might be work looking into the carburetors once again to double check the high speed jets as any restriction there would result in the problem you mention.

Another cause of that type problem would be having the carburetors open too soon in relation to the timing (synchronization). Hopefully a Force technician will jump in here with more reliable information.

Joe (30+ Years With OMC) "
 
" M,

I would advise you to


" M,

I would advise you to follow Joe's instructions; that is exaclty what I would do. I'm not a Force expert, but have worked on quite a few of these engines.

I don't have anything to add at this point. I would like to hear your response to Joe's recommendations first, but I have a few questions.

What do the spark plugs look like? Do you notice anything odd about their appearance after running for a while? Do they all look the same?

What color are the power packs and ignition coils?

How many wires lead from the trigger to the terminal strip and what colors are they?

What color are the wires from the stator to the terminal strip?

I want to try and figure out exactly which ignition components you have there. Most of these parts are only available from rebuilders now, in fact, even Quicksilver sells rebuilt components as if they are new units.

Tony "
 
" Msutphin: Does this engine

" Msutphin: Does this engine have seperate stators for low speed and high speed ignition? If so, perhaps something is wrong with the high speed stator windings. My neighbor has a 120 HP Merc (Force) which had a bad low speed stator coil. His motor ran only at high speed! "
 
" From the year stated, it is

" From the year stated, it is the old Force ignition system. I have run across a few Force motors that acted very strange. What I found was the little plug in connectors, to and from the CD Unit, were not making a good connection. I went ahead and removed the connectors and soldered all the wires, instead of using some kind of connector. This solved the problem. I'm not saying this will solve your problem but it is a good thing to look at. I do have the Force service manual for that motor in case you need any specs. There were two different systems on that motor. One used the plug in connectors on all ignition components. The other used mostly terminal blocks and a few plug in connectors. "
 
" Msutphin...I have serviced a

" Msutphin...I have serviced a few of these motors and they are not merc's best creations, they can be a real nightmare to repair. I think Tom is on the right track by replacing the wire conntors on the terimsl bar. A proper service manual is a must. You should have a prestolite ignition system on this motor, check ALL ground wires and make sure there clean and tight. You most likely have an ignition failure,possibly the stator but not 100% sure. There should be an ignition update kit for this motor to convert to a merc style ignition {if still available} although pricey it would be worth the cost if you plan to keep the motor. The best way to get rid of this headache is to replace the whole motor with a newer non force product. Hope I,ve been helpfull...GOOD LUCK...DJ "
 
"M et al,

The "A" m


"M et al,

The "A" models had plug type connections; the "B" models had screw on connectors. It would be helpful if we knew which type we are dealing with here, but the ignitions systems are functionally identical. The stator would not have high and low speed windings, unless it has been replaced with an upgrade of some type, but that is unlikely. The stator that Quicksilver sells for these engines is listed as a replacement for the original, but in reality it is a rebuilt unit from CDI Electronics, distributed by Rapair. I recently sent one back to Mercury, because the price from Merc was about $150 more than the price from Rapair. It was obviously the same product right down to the instruction and troubleshooting sheet that they include with the rebuilt units.

By the way, Mercman is right; these engines are awful and are famous for giving mechanics headaches.

Tony"
 
I agree with Tony...These eng

I agree with Tony...These engines were awful. They are best used as a boat anchor..
Gary
 
Had a 50 merc that did that. F

Had a 50 merc that did that. Found a ton of carbon from running the motor at trolling speed too much. Whole coffee can of carbon build up.
Worth a check.
 
I've had this sucker running a few times ran really good 3 days in a row. Took it out a week later it gets to the middle of the lake and hasn't ran since. Looking at the trigger wires revealed that two had probably shorted to ground. Not good!
 
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