Indianapolis help needed.. Force 85Hp

[RichardM]

I have a 1983 Force 85hp (3cyl, 2-stroke).  Ran well until last month when it seemed to be running on 2 cylinders.  While idling I pulled the top plug wire and there was no change.   I changed the plug.. no difference.  I assumed I had no spark (bad assumption).  I changed the ignition coil and the CDI (Ebay used parts).  I checked and had plenty of spark.  I rearranged my coils and CDIs and it made no difference.  I could still pull the top plug wire at idle with no or little change in the idle.  I did a compression check and all looked good.  All cylinders around 140.  I checked the fuel pump and all good with plenty of fuel in the bowl.  No obvious sign of damage of the stator.  I tried to get some help at the local dealers but no one will look at a 40 year old motor.  Does anyone have any suggestions or know of someone in the Indianapolis area who works on old motors?   Thanks……… Rick… riks44@hotmail.com

[billw]

A Force 85 doesn’t have much street value, so pros know that they will quickly exceed the value of the motor, if they try to fix it. The fact that it has compression on all three, with the symptom you describe, kind of surprises me. They lost piston rings left and right.

It’s always best to do an open gap, cranking spark test on all three cylinders at once, if you have the proper tool. However, you can try this….Run the motor for awhile and then remove the spark plug on the questioned cylinder. Tap it in the palm of you hand. Is there water? You might have a leaking head gasket. Is it dry? You might have a bad carb. (I believe that has three carbs, right?) Is it wet? You might have a flooding carb or a leaking fuel pump diaphragm. If it’s dry, you might also have a bad reed but that’s a long shot. Write back with results of this test.

Long live American manufacturing!

[RichardM]

Thank you for our reply.  A new wrinkle has arisen.  I started it up today and the water pump wasn’t working.  I did pull the plug and it was wet but didn’t look any different than the other plugs.  I tried to see if it was flammable.  It wouldn’t ignite with a lighter … but the other plugs wouldn’t either.   I first thought it was rings or the head gasket but the 140 PSI threw me.   I got 30 years out of this engine so I can’t complain but I don’t like giving up.  I’d like to know for sure if it’s done but I need to find someone smarter than me (the marina guys don’t even return my voice messages)…. or I may just take it apart as a learning experience but I’ll never get it back together.

It was a good engine up to 5 weeks ago… never left me stranded.  40MPH on my Bayliner Capri.  Oh well, all good things must end.

 

[billw]

Another troubleshooting trick that I forgot to mention is to use a metal pump oilier, (a squirt can made to oil machinery) full of two stroke gas mix, and squirt it into each carb throat while running. If the cylinder comes alive for a second, then you probably have a lean/dirty carb on that cylinder. This doesn’t work well at idle because it will flood the cylinder just as fast as making it less lean. It works better underway, if you can get a helper to drive the boat.

Long live American manufacturing!

[RichardM]

Thanks.. I tried that but it stalled the engine.  Didn’t try it high RPMs.  Ill probably replace the impeller and try again.

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