{ HELP!!! No Spark, OMC 120 }
Steve Owen
Can anyone help, I just got a fixer upper and the OMC 120 in/out has power
to and from the coil but not enough for spark all tests show that the
current should be flowing correctly but still no spark. The boat is a 1976
Sea Shark 18' and had been setting for more than a year. Is there anyone to
answer this.
We don't have allot of money I got the boat for the kids in our area that
was causing trouble sense we got this boat they have stopped causing
problems. They have had a great time working on the boat, cleaning and
repairing. I hate to have to tell them that the boat wont start now that
their almost done getting it ready for the water and taking boat safety
classes.
Please help!!! Thank you Steven Owen
Dave Brown
Steve Owen wrote:
Pull the coil wire out of the distributor cap and hold the end within
1/2" of a good ground (the engine hook works well on this motor). Have
someone crank the engine and observe if there is spark. Got none? Run a
jumper lead from the positive terminal of the battery to the positive
terminal (+) of the coil and try the test again. Let me know the results
of these two tests and I'll direct you from there. before going much
further, are you comforatble uing test lights and replacing points etc.?
If not, bow out now and get a dealer to look at it. These ignition
systems are extremely easy to diagnose and it shouldn't cost too much to
have it up and running again.
Regards,
Dave Brown
Brown's Marina
GREGORY J VISHEY
all tests show that the
>current should be flowing correctly but still no spark.
Spark is generated by pulsing 12Vdc into the primary winding of the coil and
stimulating a high voltage out of the secondary. If the point gap in the
distributor is excessively open or closed, the points will not "chop" the
12Vdc into the primary coil...and you will get no high voltage.
1. Check that the point gap is correct and that the points are undamaged.
As a general rule, install new points and condenser before advancing to
other trouble-shooting steps.
2. Let's assume that 12Vdc gets to the distributor now and that the points
are okay. The 12V ac lead (not the high voltage wire) goes to the coil
primary winding. The other side of the coil goes to ground. Measure the
resistance across the two terminals and verify that it is low (0-5 Ohms for
example). If the measurement shows open, you have a bad primary in the
coil...get a new coil.
3. Let's assume that the primary windings are okay. Take your Ohmmeter and
measure from the HIGH Voltage output at the top of the coil to ground (yes,
turn the ignition off!). Verify that it is low resistance too. If the
measurement shows open, you have a bad secondary winding in the coil...get a
new coil.
4. Let's now assume that the electrical path to this point is
correct...There should now be spark. If there is not...is the rotor in
place in the distributor or did someone forget to put it in? Check the
STATIC TIMING by rotating the 1st cylinder to TDC on the compression stroke
and verify that the rotor points in the direction of the #1 cylinder wire in
the distributor cap. Then verify that the wiring from the cap to the spark
plugs is correct.
> Many problems arise from removing wires and installing them in the wrong
order.
> Many problems result from removing the distributor then re-installing it
out of position.
> Points frequently burn or fuse and fail...they are cheap to replace.
If you get the engine cranking but still no firing...(and still no spark off
the plug) try a replacement wire to verify that the distributor wires are
not failed.
Good luck,
Greg