Force 75 threw a magnet at us

[Teseal]

Let’s see if I can sensibly describe my outboard problem so someone can suggest where I go next:
Bought this 1997 Force 3 cylinder 75hp on a bass boat. First go over; fuel system all new, filter replace, plugs ok, compression low at 115 but all the same, started and ran on the water hose no problems noted. On the first lake run which only lasted maybe 10 minutes, motor started and idled OK, during acceleration some point just off Idle the motor vibrated, once past that point it seemed smooth but again at an intermediate throttle level it returned but quit as we accelerated thro. WOT throttle gave us about 30mph if the speedo is right. Stopped on the lake to remove the cowling to inspect the random vibration. When I started it up a magnet came flying out at us, we paddled back to the landing.

I opt to replace the one completely lost magnet and the 2 damaged ones rather than replace the flywheel. Checked as best I could the static balance which I know can be the downside. Also replaced the stator. Started and ran on the water hose seemed a bit rough but wanted to lake test. On the lake it seemed to be missing at idle and intermediate throttle but seems smooth at high end.

Carb cleaned and inspected, spark tested all three arching ½”, cold checks on the stator and trigger good, also on regulator, although I question the regulator drawing 25ma from the battery when expect it should be less than 1ma. Ran with each plug disconnect, with #1 only a slight diff, with #2 it was a bit more noticeable that meaning rougher idle, #3 it would barely idle. Swapped CDI coils 1 and 3 but symptoms did not change #3 still effect the idle to the point where it would eventually kill and #1 very little effect.

Add this symptom to the mix, sometimes the tach will not work, sometimes it drifts, sometimes it will change without a motor rpm change. I don’t know if the boat has the right type of tach for this motor, it is a Teleflex and has the pulse selector on the back but the label for pulses is missing.

I want to replace regulator because of what seems to be a high battery draw even without knowing how it will charge the battery and the possibility it is related to the tach symptoms, but I don’t believe this is related to the rough running problem.

Something else to add to the mix, the data tag has been removed from the motor so we don’t have a sn# but we did find a mfg inventor tag on the power head indicated it was tested in 1997.

I sure am open for suggestions and expect the first will be "bit the bullet and buy a flywheel".

 

[pnwboat]

Not sure that I'd go out and get a flywheel just yet. The fact that you are getting what appears to be good spark, probaly means that the Flywheel magnets are doing what they are supposed to do.

The tach issue may be an indication of either a problem with the tach, or the Rectifier/Regulator.....or maybe a bad connection. If the connections on your Rectifier/Regulator are the cylindrical bullet type connectors, I've seen many of them where the clear plastic sleeve on the connectors is darkened from heat due to a poor connection. A bad rectifier/Regulator can cause ignition system problems. I believe this is due to the fact that the charging system coils are also located on the stator assy. If your connections are OK, and you can confirm that it's not the tach itself, then I would lean towards replacing the Rectifier/Regulator.

One other question...what are your RPM's at WOT?

 

[Teseal]

Thx for your reply. Not so sure I can say what the revs were. I only had it opened up once and because I wasn't sure if the tach was right I didn't stay there but a second. When the tach was stable it was about 5200. I did order a new regulator so we'll have another look in a few days.

I did have concerns about the tach bothering the engine so I tested with it disconnected but there was no apparent difference.

 

[jerryjerry05]

If the magnets(even one) come loose?? then
the rest are probably gonna follow
The flywheels are rare and pretty expensive.
Fact: you'll probably find a complete motor for
the price of a used flywheel.
Saw one on FB Marketplace for $550
new they're 600+
The flywheel fits a LOT of different motors so look
around, you might find one and the seller doesn't
know what he's got??

 

[Teseal]

Yeah good point about the cost, might look for a complete outboard if the regulator doesn't help. Thx

 

[pnwboat]

Is this what your flywheel looks like?

 

[Redbarron%%]

That appears to be a late model flywheel ~1996+, but I have been wrong before. The trigger magnets would be different between the earlier CDI and later CDM engines and the diameter of the crankshaft would also be larger. It would probably fit a 1997 75 hp 3 cylinder engine.
IIRC.

 

[Teseal]

That appears to the flywheel, but I don't believe you can tell the difference with the trigger magnets. Guess I should say I don't know how to tell if it's one row or two. I do know by part number research that the 1996-1999 all used the same flywheel, any one of 6 different units.

 

[pnwboat]

The flywheel pictured was one I had purchased years ago for an ignition system upgrade. This particular flywheel fit the late model larger diameter Mercury style crankshaft, which was not what I needed. I went out to my shop, but it was nowhere to be found. It was not sitting with all my other flywheels....so I must have gotten rid of it. Darn! Anyways, I did see some guy selling just the flywheel magnets on line....$75 a piece...... six of them....LOL! They're probably a liitle chewed up from being pried off the flywheel.

 

[Teseal]

Sorry to hear that you couldn't come up with that flywheel but I sure appreciate you looking. Not sure why the Force ones have turned to "gold."
I should get the replacement regulator tomorrow, I'll get it in right away, test, and update.

 

[jerryjerry05]

They're gold because they only used them for a limited time.
The older Prestolite ones were used for 10-12 years and millions were
used on the different Chryslers and Forces.
They fit 50hp 85/90 120/125 and 150hp.
Yours fits a bunch of motors from Force to Mercury, to Sport jet, Mariner etc.
I can send the link to what it fits. But it'll come in a PM

 

[Redbarron%%]

The late flywheels with the raised center and larger bore have a different arrangement for the trigger magnets and the trigger coils have the bias circuit built in where the older CDI have the bias circuit in the CDI box, making the swap from CDI to CDM more problematic.
The outer magnets are the same, however.
Since I operate a 95 Sport Jet I "collect" most good flywheels I find.
The problem in my mind is that the Iron flywheel rusts under the adhesive that secures the magnets and they eventually turn loose.
If one magnet comes off then the rest are on the way as well.

 

[Teseal]

Got the new reg/rect installed. No battery draw with everything off, (old one was at 25ma). Not sure how to prove it’s doing the battery any good, before starting battery was at 12.5v. Rev’d the motor a bit and it didn’t change, at that voltage maybe it shouldn’t (?). It's Sierra and has 2 red leads one male connector one female my old only had 1 but the motor wire harness connector is a female so used the male. I believe the second red wire was just a source for 12v for other models. Anyway that was the least of my concerns, it didn’t seem to help the motor any, no tach signal, and still running rough vibrating the whole boat, any rpm. I did jack the low speed jet a bit and it did respond some, rpm increased as I leaned it out. I checked to see where it was at after shutting down and a bit surprised it was only open ¼ turn. Maybe I should try to disable that enriching ckt used for starting (?). I’m guessing now that some of the vibration is mechanical from the flywheel but don’t see how that would make it run so rough. Sometime prior to leaning the mix the engine would cough, rpm would reduce and slowly advance back. Hadn’t noticed that before.

After installing the new reg the tach wouldn’t move, it would 0 when I turned the key on but that was it. Tried changing the setting on the tach but no change, possibly the tach has failed.

Anyway not sure where to turn next or if there’s another option before finding a different flywheel? Possibly seafoam?

I expect the motor sat for 3-4 years before we bought it, the registration on the boat it was on expired in 2016 but the seller said his Dad had it out in the summer 2019. We bought it in Jan this year.

You guys have been great with your comments , suggestions, if you got any more I’m listening.

 

[Teseal]

Got the new reg/rect installed. No battery draw with everything off, (old one was at 25ma). Not sure how to prove it’s doing the battery any good, before starting battery was at 12.5v. Rev’d the motor a bit and it didn’t change, at that voltage maybe it shouldn’t (?). It's Sierra and has 2 red leads one male connector one female my old only had 1 but the motor wire harness connector is a female so used the male. I believe the second red wire was just a source for 12v for other models. Anyway that was the least of my concerns, it didn’t seem to help the motor any, no tach signal, and still running rough vibrating the whole boat, any rpm. I did jack the low speed jet a bit and it did respond some, rpm increased as I leaned it out. I checked to see where it was at after shutting down and a bit surprised it was only open ¼ turn. Maybe I should try to disable that enriching ckt used for starting (?). I’m guessing now that some of the vibration is mechanical from the flywheel but don’t see how that would make it run so rough. Sometime prior to leaning the mix the engine would cough, rpm would reduce and slowly advance back. Hadn’t noticed that before.

After installing the new reg the tach wouldn’t move, it would 0 when I turned the key on but that was it. Tried changing the setting on the tach but no change, possibly the tach has failed.

Anyway not sure where to turn next or if there’s another option before finding a different flywheel? Possibly seafoam?

I expect the motor sat for 3-4 years before we bought it, the registration on the boat it was on expired in 2016 but the seller said his Dad had it out in the summer 2019. We bought it in Jan this year.

You guys have been great with your comments , suggestions, if you got any more I’m listening.

I'm an a**, you can forget the symptom where I mentioned it would cough and lose rpm. I was setting up to do the seafoam cleaning and thought I would inspect the plugs first, bottom plug was not tight. I had the plugs in and out a bunch of times and don't recall the last. So here's where I'm at after install ALL the plugs, rough at low end, vibration mostly at lower rpm, tach not working with new reg, I only rev to approx 2k on the hose and hear a miss, still going to run the seafoam thro it tomorrow.

 

[Redbarron%%]

The tach will operate from either the gray wire from the rectifier/regulator or tapped directly off one one of the yellow wires from the coil.
You might want to verify spark plug current on each wire. An inductive timing light clamped over each in turn should verify spark on each cylinder under load.
You can do a drop test by starting with one plug wire off and grounded and see if one off makes more difference than the others.
A dead cylinder, disconnected, will make no difference in running.
Disconnect one working cylinder of three will be very noticeable.

 

[pnwboat]

Just a thought....I've seen quite a few of the 1995 and later motors that have
broken/cracked a reed petal or two.

 

[jerryjerry05]

My opinion: Seafoam's a waste of $$
I use Chevron with Techron. Black bottle, looks
like an upside down funnel.
Mix it with 1/2 gal gas. and run through the system.
The primer has a diaphragm inside and it can leak
fuel into the carb and cause poor running at all speeds.
Once it's running, pinch off the feed to the carb and
see if that makes a difference??
I bought a snake cam for my phone(11$) you can look
inside the carbs and check the reeds without removing
the carb. The 75 with one carb is kinda hard to see the
reeds.

 

[Teseal]

Thx Redbarron, I did isolate the cylinders earlier; " Ran with each plug disconnected, with #1 only a slight diff, with #2 it was a bit more noticeable that meaning rougher idle, #3 it would barely idle. Swapped CDI coils 1 and 3 but symptoms did not change #3 still effect the idle to the point where it would eventually kill and #1 very little effect." After looking for info regarding the response someone had mentioned that at idle this was characteristic of a 3 cylinder engine with one carb. Comments?

How would you inspect the reed valves pnwboat?

 

[Teseal]

If the seafoam doesn't make a difference I think what I'll do is try to find a seller on ebay that would rent me their flywheel, if it works I buy it, if not I pay a fee and send it back.

 

[pnwboat]

You can do like Jerry says, if you have access to a bore scope/snake cam, you can go through the carb...or take if off and go through the adapter plate/intake manifold to inspect the reeds. They sit right underneath the carburetor. Thery're kind of hard to see on the 75HP motor because of how they are sitting under the carb.

Otherwise, to inspect the reeds, remove the carburetor and adapter plate/intake manifild that the carb sits on. You'll see the reed plates. There are 3 of them. One set for each cylinder. There is a gasket on top of and underneath the reed plate assy. If you're carefull and don't damage the gaskets, you can re-use them. Otherwise they're available. About $10 each.

A broken reed petal will usually be more noticeable at lower RPM's because of slower air flow as opposed to higher RPM's. They act as one way valves for the fuel/air mixture to keep it going into the intake ports in the cylinders.

NOTE: If you suspect a leaky Primer solenoid, you can eliminate it by simply disconnecting the fuel line going to it from the carb. bowl and plugging the line (to keep fuel from leaking out of the fuel bowl) to see if it has any affect.