Howdy outboard guru's, I've got a little story here with some twists that
you may be able to comment about and help me out.

Lets begin with the background.. 1972 80HP Merc. It was identified that
ignition troubles are the culprit as spark was noticed to be an issue.
(would start sometimes, sometimes not, or when running would just die)
Assuming that there are 3 main components that could be a problem I have
been considering all of them and some of them a problem: coil, or switch
box, or trigger.

Serious tests, - Day 1.
Fortunately I have the original service manual of the era for this motor.
It actually has a page dedicated to testing the ignition of this beast
pretty much as follows:
- move engine to TDC
- connect spark plug type tester to wire #1 and ground it.
- remove the blue wire from the switchbox
- turn the key to the on position, verify the ignition wire which
indirectly goes to the trigger is on.
- ensure the red wire to the switch box is on too.
- ground a wire with clips, and touch the other end to the blue
connector of the switch box. When you then remove the wire from the
connector a spark should be visible at the spark plug tester.

Day 1 determinations:
- the above test was done and there was spark evident, so that had bypassed
the trigger.
- next put things back except for plug #1 with the spark tester on it, and
turned engine over to start. No spark visible right away, but then it came,
and went just as quick
- tried the original test again, same conclusion, spark.
- did the other start mode try again, same conclusion, spark but only once
in a while,
- tried the original test again, you get the idea, did this switch back and
forth 5+ times.

Day 1 conclusion: since spark was always present during the trigger bypass
test, and spark was only sometimes present with the normal operation using
the trigger, it was concluded that there's a high chance that the trigger is
the problem for this unpredictable spark. Next steps, remove distributor in
order to try and find parts..

Day 2 - Serious tests.
- When the distributor was out I became interested in seeing exactly how the
trigger functioned. It would appear that 4 sections on the shaft existed
which were protruding out more than the rest of the collar. These four
areas would come very close by the trigger (which is encased in plastic
anyway), I assume they are just metal or something. Well these 4 sections
also had a rust coating on them, so I took the rust off, and thought hey,
why not just try this again as maybe it would change something seeing I
couldn't look for replacement parts today anyway. So that's what I did.
Also to note, as these are not electrical contacts, it may not even matter
about the rust, and I could be wasting my time.

After putting it all back in, the intention was to try and start the motor
up. So, this was attempted, and yes the motor did start, but then quit
abruptly. The next steps were to check for sparks in the two ways as
covered in day 1.

Day 2 - determinations.
- initially the trigger bypass test yielded some spark on plug number 1,
but this stopped occurring after a few sparks.
- when turning the engine over as to start, no spark existed, except for
occasional once again.
- tried this over and over again, both ways.

Day 2 - Conclusion
- it can't be the trigger now, as problems existed when it was bypassed.
This ghost problem would appear to be elsewhere in either the switchbox, or
coil. Fortunately this ghost problem re-appeared this way before I got a
new trigger.

Next Steps:
Without testing the switchbox, it is hard to say where the problem is.
Likewise the coil. The coil I had gotten on the motor was taken to a shop a
few weeks earlier and put on the merc tester. The result, zero spark when
it should have had some, so the conclusion was that it was garbage. The
current coil on the motor was a used replacement for testing which when
tested alongside the old coil yielded the result of spark once, twice, but
not a third time when tested on the machine. This odd behavior makes me
think that perhaps the coil shuts down after a few sparks. Then it works
again to some extent later. In any case, I put it in as it does give some
spark, and thus far ended up demonstrating that my motor can run .

So, right now I'm back to square one where I need this coil retested, and
likely need to get another one prior to saying its the switchbox. Of course
if I had a place here that could test both the coil and switchbox (under
load as it would show the ghostly problem) then I may be able to get
somewhere.

What do you guys think?

It would seem bad to me to spend money on a new coil, a new switch, and a
new trigger.

help.

Does anyone know what current should be heading from the switch on the green
lead to the coil +?


"Chris" wrote in message
...
Howdy outboard guru's, I've got a little story here with some twists that
you may be able to comment about and help me out.

Lets begin with the background.. 1972 80HP Merc. It was identified that
ignition troubles are the culprit as spark was noticed to be an issue.
(would start sometimes, sometimes not, or when running would just die)
Assuming that there are 3 main components that could be a problem I have
been considering all of them and some of them a problem: coil, or switch
box, or trigger.

Serious tests, - Day 1.
Fortunately I have the original service manual of the era for this motor.
It actually has a page dedicated to testing the ignition of this beast
pretty much as follows:
- move engine to TDC
- connect spark plug type tester to wire #1 and ground it.
- remove the blue wire from the switchbox
- turn the key to the on position, verify the ignition wire which
indirectly goes to the trigger is on.
- ensure the red wire to the switch box is on too.
- ground a wire with clips, and touch the other end to the blue
connector of the switch box. When you then remove the wire from the
connector a spark should be visible at the spark plug tester.

Day 1 determinations:
- the above test was done and there was spark evident, so that had
bypassed the trigger.
- next put things back except for plug #1 with the spark tester on it, and
turned engine over to start. No spark visible right away, but then it
came, and went just as quick
- tried the original test again, same conclusion, spark.
- did the other start mode try again, same conclusion, spark but only once
in a while,
- tried the original test again, you get the idea, did this switch back
and forth 5+ times.

Day 1 conclusion: since spark was always present during the trigger
bypass test, and spark was only sometimes present with the normal
operation using the trigger, it was concluded that there's a high chance
that the trigger is the problem for this unpredictable spark. Next steps,
remove distributor in order to try and find parts..

Day 2 - Serious tests.
- When the distributor was out I became interested in seeing exactly how
the trigger functioned. It would appear that 4 sections on the shaft
existed which were protruding out more than the rest of the collar. These
four areas would come very close by the trigger (which is encased in
plastic anyway), I assume they are just metal or something. Well these 4
sections also had a rust coating on them, so I took the rust off, and
thought hey, why not just try this again as maybe it would change
something seeing I couldn't look for replacement parts today anyway. So
that's what I did. Also to note, as these are not electrical contacts, it
may not even matter about the rust, and I could be wasting my time.

After putting it all back in, the intention was to try and start the motor
up. So, this was attempted, and yes the motor did start, but then quit
abruptly. The next steps were to check for sparks in the two ways as
covered in day 1.

Day 2 - determinations.
- initially the trigger bypass test yielded some spark on plug number
1, but this stopped occurring after a few sparks.
- when turning the engine over as to start, no spark existed, except
for occasional once again.
- tried this over and over again, both ways.

Day 2 - Conclusion
- it can't be the trigger now, as problems existed when it was
bypassed. This ghost problem would appear to be elsewhere in either the
switchbox, or coil. Fortunately this ghost problem re-appeared this way
before I got a new trigger.

Next Steps:
Without testing the switchbox, it is hard to say where the problem is.
Likewise the coil. The coil I had gotten on the motor was taken to a shop
a few weeks earlier and put on the merc tester. The result, zero spark
when it should have had some, so the conclusion was that it was garbage.
The current coil on the motor was a used replacement for testing which
when tested alongside the old coil yielded the result of spark once,
twice, but not a third time when tested on the machine. This odd behavior
makes me think that perhaps the coil shuts down after a few sparks. Then
it works again to some extent later. In any case, I put it in as it does
give some spark, and thus far ended up demonstrating that my motor can run
.

So, right now I'm back to square one where I need this coil retested, and
likely need to get another one prior to saying its the switchbox. Of
course if I had a place here that could test both the coil and switchbox
(under load as it would show the ghostly problem) then I may be able to
get somewhere.

What do you guys think?

It would seem bad to me to spend money on a new coil, a new switch, and a
new trigger.

help.