1990 120 lost power, erratic tach, now wont start

[pelletman]

Engine has been running fine for 2 years when I tried to pull a skier and had about half power at full throttle. At same time I noticed the tach was buried beyond 6000 rpm and read 500 rpm when engine was off. We were able to run engine for a few minutes at which time power returned and I assumed we had a fuel issue of some kind. After shutting engine down I was unable to restart and had to paddle in.

Since then, I replaced fuel filter and pump seals and diaphragm. and changed plugs. In checking spark, number 1 was not firing. Based on info from outboard ignition.com I checked stator and trigger resistance and both are within spec. After replacing my rectifier and coil pack on #1 cylinder, I now have a solid reading on tach. (0 at rest, and about 300 while cranking). And all plugs are firing. But I hear no "popping" or attempt to turn over. Checked reeds earlier because gas flowed out of top carb. They also look fine. Compression was near 125 on all cylinders last time I checked.

What next ? Anyone ?

 

[jerryjerry05]

Unhook the tach and see if that makes a difference???

​The stator OHMS can read ok but the output voltage not be right.
You need a DVA meter or an attachment for your analog meter.

Test the flywheel key and see if it's sheared.
Do a compression test, it can change from 1 trip to another.

Try tilting the motor all the way up and see if it starts while up??
Squeeze the ball while up.
Sometimes the floats BOTH lock in place and no fuel gets in??

 

[pelletman]

Thanks for the input. Tried removing the tach, no effect. I gave up this morning and dropped the boat off at a local mechanics. My bet is on the stator, but maybe the floats.

 

[Derrick Fronckowiak]

Interesting....I wouldn't bet on the stator IF you are getting good sparks on all cylinders and your tach is reading right. How are you checking your sparks? Spark board? Inductive timing light? As jerryjerry said check your DVA voltage. Also check ALL of your terminal connections (the terminals can get brittle where the wires attach to them). Also, as Jerry said, check your flywheel keyway to see if it's sheared (I had one shear once and couldn't tell until I got the flywheel off, bits and pieces of the key everywhere, my fault because I didn't ensure the flywheel was all the way on and fully torqued). Your tach gets it's signal from a lead that comes right off of your rectifier. The signals (pulses) coming off of your stator (for your battery circuit, NOT your ignition charge coils) are proportional one-to-one (one revolution, one pulse), that's how your tach gets it signal for RPM. Your tach "circuit" is NOT tied in with your ignition circuit at the stator (they're totally separate). Sooo, it seems you've fixed a few thin, but as Jerry alluded to is your issue ignition, or fuel, or worse yet mechanical (comp check, and flywheel keyway). Check the simple stuff before the mech tells you to replace expensive components. If he tells you to replace components ask him how he determined the component was bad (gut feelings don't count-results should be measurable, low/no DVA voltage, high resistance, open, short, no ground, fried, fuel path restricted, etc.).

 

[Derrick Fronckowiak]

One more thing, I'm a newby to all of this too, only been boating a little over two years, but the expertise on this forum is invaluable!!!!! There is a whole lot more collective wisdom/experience here than you can imagine and I can say that I have saved several hundred dollars (so far) by listening to the sound, sage advise I've gotten herein. They don't make some of these engines anymore, so we really have to rely on the others guys who have owned them in the past or presently own them. Before you component swap/change (spend moolah) listen to some of these guys they've likely dealt with some of the issues we're experiencing at some time in their past.