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TOPIC: 40hp 1975 no spark to the 2ed plug Help please !

40hp 1975 no spark to the 2ed plug Help please ! 1 week 4 days ago #143376

40hp mercury 1975ish no spark to the lower plug
i checked the plug wire it is ok
i switched the good coil from the working spark plug to the other one and it did not work ether so coil is ok as it worked when i plugged it into the working one
the switch box connections were very corroded i cleaned them all but still no spark in the one plug
Also, i notice on the coil that does creat a spark there is an extra black wire to the negative terminal but not a wire on the coil where the plug does not create a spark. Anything strange about that ??
i do not know much at all about engines etc.
I have a video of some tests i tried to do from what i did can any educated guesses be made on the problem of no spark to the 2ed plug? this is the address of the you tube video

thanks

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40hp 1975 no spark to the 2ed plug Help please ! 1 week 4 days ago #143379

The 400 and 402 have gained infamy as a "401" due to ignition failures.
Your switch box looks like it might be the same as one I just stripped of an '85+ 40? 35? 2 cyl.
Mine might be okay, but since the motor was seized, I was unable to test it.
Post your serial number, and I'll cross the parts ith my seized one.
If my parts are the same I'll ask for a PM for your contact info, so I can determine where to ship my parts to on my dime.
If my parts resolve your problem, I will want 25% of list cost + postage.
If my parts don't resolve your problem, just throw my parts away.
doc

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40hp 1975 no spark to the 2ed plug Help please ! 1 week 4 days ago #143381

sounds good but mine has the posts coming out of the box. i guess that might not matter i will get the number thanks

I looked things up on marine engine .com i think it is better to stick with the cdi box that has the studs vs yours with the wires coming out to connect to.

and also it this time i am not sure if that box is the problem

thanks for the offer

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40hp 1975 no spark to the 2ed plug Help please ! 4 days 20 hours ago #143401

OK after fooling with the wires i now have spark to the 2ed plug but it still only cranks .... it does not turn over and run

what are the next things to check.

here is a link to a few seconds of it cranking. i dont know if the throttle and choke are in the correct position

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40hp 1975 no spark to the 2ed plug Help please ! 2 days 11 hours ago #143403

If the spark won't jump about a 3/8" gap,...It's not going to fire.
Track down the specs and Ohm & DVA the ignition components.
doc
The following user(s) said Thank You: joecffv@aol.com

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40hp 1975 no spark to the 2ed plug Help please ! 1 day 13 hours ago #143405

SO i got help be someone reminding me hat the gas tank need to have the cap vent opened. And i did use some starter fluid into the carburetor. SO it sprang to life
BUT >.... no water out of the pee hole

So i figured i did not the copper tube back on correctly and pulled the lower unit off and reattached it hoping it connected correctly. Who got paid to design a connection that you have to guess at if it connects or not
HAs anyone tried cutting out a little piece of the shaft housing so you could see the water tube connect or something ???????
Anyway, tried starting it again AND now i'm bck to NO SPark *******
SO im thinking there is a loose wire in the stator or trigger from some videos i looked at. Next I'm going to pull of the flywheel to test things. any suggestions would be appreciated
if you want to look at ir running here is a video link

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40hp 1975 no spark to the 2ed plug Help please ! 16 hours 48 minutes ago #143411

ok next step
am trying to get the flywheel off this is way way hard . I bought a puller and tightened as much as i can almost thinking things will break and fly everywhere. it does not want to budge, sprayed in lubricant also
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40hp 1975 no spark to the 2ed plug Help please ! 2 hours 20 minutes ago #143412

DONT USE THAT PULLER ! If you don't have the correct puller us a puller attached to 2 bolts removed from the center hub. using your puller can ruin or break the flywheel.

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