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HELP...1982 Mercury 70 hp appears to have no spark

G

goosemanhnt4fud

New member
Hello everyone,

Newbie here...
Yesterday morning I took the boat out and it ran fine. Yesterday afternoon I took it out again, and it would not start. Today I tried to trouble shoot it. This is what I did:

1. Fuel pump is working, removed the line from pump to carbs,(carbs were cleaned two weeks ago) and it is squirting out gas.
2. Compression check is 146/146/147
3. I removed the spark plugs, and they were dry. I squirted some fuel in the #1 and #2 cylinders and tried to start it, but it would not fire.
4. I made sure the kill switch was in the run position.
5. The inline fuse on the hot wire that goes to the rectifier, fuse is good, and as I attempt to start the yellow wire that goes to the stator has power. (the stator does have some dry rotted wires)
6. all three spark plugs are new
7. Took a spark plug out, and turned over the motor and saw no spark.

What is my next step? Is there anything else I should look for, i'm pretty mechanically inclined...just looking for some light at the end of the tunnel...
Thanks in advance for all the help.
​
 
Check the other cylinders for spark. If you have no spark anywhere -

Get ahold of a Seloc's manual and grab an ohm meter (or multi-meter) and do the resistance tests for the stator, trigger and coils. If they all check out ok replace the switchbox.

Don't try and short-cut and replace the switchbox. At $220 bucks you don't want to simply swap it and find you have a bad stator (a mere $185).

You can not test the switchbox, so you have to verify that all other ignition components are working to determine it's the problem.

I don't have the resistance values/test sequence for your particular model or I would post it up for you (which is why I suggest the Seloc's manual at $35 - good to have anyhow)
 
I also tried something else too...i tried the removal of the kill switch wire, from the switch box and the mercury switch and tried cranking her over...nodda...

I did notice the yellow wire from the stator, is almost completely dry rotted thru right at the stator...which i am assuming is not good...does anyone know what that wire is for, the purpose of it, it goes right down to the rectifier... ???

Looks like i need to purchase one...should anything else be changed along with the stator?

I will get a tester and do the tests on the other wiring too

Thanks for all the help...
 
That yellow wire from the stator is only for battery charging--no battery power is used to make spark.

I suspect your stator is fried. Remove the blue and red wires from the spark box and check them with a meter. If they are open, is shot.

Jeff
 
fastjeff,

you said remove the blue and red wires, if it's open then the stator is shot, does it matter which wire i put the leads from the tester on? I have a dm-20 greenlee,
dm_20.jpg

what will the read out say when it would be "open"....I am guessing Zero??? I am pretty new to all the ohms/electrical side of mechanics.

Thanks again for the help to all!!
 
Well guys, i took the red and blue off the switchbox, and the meter read 6.65...
b54c2d8b.jpg


I'm not sure if that is good or not...?

Any suggestions??
 
That is good.... and bad (for you). Next, remove the 4 wires on the left side of the switchbox (violet, brown, white, etc.) and see if they have continuity as well. Try each wire to ground and to each other; and make a list of the results dso you dont confuse yourself.

Jeff
 
So what do you think is the matter with it so far, did we rule out the stator being bad, or is the resistance on the stator good enough? when we check each wire to ground, we are checking to see if it is has shorted?

Just trying to follow along the troubleshoot skills you guys possess and that I lack in this situation. Trying to learn...

I checked again last night if there was any spark at all from any of the three cylinders and there still was nothing...

Thanks for all the help!!
 
Well, here are the numbers:
Top white to violet: 1.3
" to white or tanish color: 1.29
" to brown: 1.29

Violet to white or tanish: 2.58
" to brown: 2.58

White or tanish to brown: 2.57

White to ground: didnt read anything not zero it just stayed the same
Violet to ground: didnt read anything not zero it just stayed the same
Tanish to ground: didnt read anything not zero it just stayed the same
Brown to ground: didnt read anything not zero it just stayed the same

Those are my findings for this step of the project...
 
Ugh! Sounds like spark box. There's a bunch on eBay for well under a hundred each. The 6 cylinder uses the same box (though two of them).

Jeff
 
So you are saying the stator and trigger are ok, correct?
As long as they are not shorted out, and show resistance they are ok?
Just trying to keep track of the troubleshooting scenario, to keep track of for future(hope not) situations...

Well I will get a new switchbox, and slap her in...Thanks so much!!
 
goosemanhnt4fud said:
Well guys, i took the red and blue off the switchbox, and the meter read 6.65...
b54c2d8b.jpg


I'm not sure if that is good or not...?

Any suggestions??
Click to expand...
Reading between red and blue should be 3.6 to 4.6 (Rx1000) Between Red Stator lead and ground 90 to 140 (Rx1) Now if you have DVA Meter which is the best way to test this system...(Stator blue low speed red test lead and then black to ground should be 200-300 volts at cranking...Stator red high speed at cranking (red test lead to red meter lead wire and black to ground 20-90 volts.... SW.Box-Stop Circuit SW (Black/Yellow with (Meter red lead and black Meter lead to ground)(200-360)volts

Steve:eek::eek:
 
It's been my experience with these mototrs (I have 3) that the "correct" ohm readings per the manual is rarely achieved, and even when the ignition is working fine. Basically, if you don't have an open circuit where there should be resistance, or a short to ground where there shouldn't be one, then the charging and trigger coils will work. The spark box tends to be the weak point on these triples, being strapped to the side of the block that tends to overheat its top cylinder due to insufficient weater flow. (The impeller is just too damn small for 70 hp!)

Jeff
 
***UPDATE***

Well I received the new switchbox in the mail yesterday, so I switched them out....and the motor still doesn't fire up....
I bought a stator and a trigger also, just in case I would have to switch those out in the future...
I did notice something yesterday, the trigger is very loose, like i can put my finger under the flywheel and move it around, is this supposed to be locked down??
Also If anyone would be so kind to tell me how to remove the flywheel, and retime the motor....just in case I have to switch out the stator and trigger, would be great...
Thanks again guys...
 
A special fluwheel puller threads into the flywheel where the nut is. Best find a shop to do this for you.--------Timing should not change by changing out those parts.
 
A conventional, two bolt puller is all I use and it works fine. Remove two of the bolts in that ring (3/8 fine) and use those holes for the puller. It's a splined connection, so the 'wheel usually comes right off.

The trigger coil fit is a bit sloppy, but it CAN'T be dragging on the flywheel or it will wear out fast.

Jeff
 
Well guys....I have had success....I changed out the switchbox and the stator, and it fired right up, I checked for spark on all three cylinders and it was nice and strong, I told myself all I need now is some fuel and we'll be all set, and sure enough it started...my first major outboard motor troublshoot/repair is in the books...Thank you all for your input/suggestions...
 
i replaced the switchbox first, check for spark, and it was really light if any, so i switch out the stator, checked for spark and it was really good, like 1000% better, i hooked everything back up and tried to fire it up, and it did almost instantly....so I would have to put my money on B, the stator....
 
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