no spark on one cylinder UPDATE!!!!

[bare3176]

I have a 25E74M Johnson that is eating my lunch!!!!!!!!!! I have changed points, condenser, plug wires, plugs and still I have no spark on my tester on the bottom cylinder. I have changed coil positions, unhooked the kill wires, set and reset the points at .020 and nothing. I got it going this morning and took it to the lake and ran about 15minutes and then stopped firing. I can get it to fire very little with a plug but nothing thru the tester at its closest setting. Everything on the upper cylinder is fine. I just tried synchronizing the points with my ohmeter with one point set at about .025 and the other set at .016 to get them 180 apart between the marks and still nothing. I need help. Thanks.

 

[AlTn]

Re: no spark on one cylinder

Re: no spark on one cylinder

will the #1 coil fire when the lead from under the f/w for the #2 coil is attached to it? < trying to condemn under f/w problem or coil> conversely..will the #2 coil fire with the lead for #1 attached?

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

I am not following you AlTn. Both coils are under the f/w. Leaving everything else the same, I can swap coil positions and have the same problem with the other coil. I have some kind of problem with the coil and points/cond. that fires the lower cyl. The only thing I can come up with is a bad magnet in my f/w.

 

[tx1961whaler]

Re: no spark on one cylinder

Re: no spark on one cylinder

Ohm out the plug wires. Make sure there are no nicks in any of the coil/condenser/points wiring. Test the condensers. Clean the points with solvent. There is only one magnet made in the flywheel and it doesn't go bad.

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

I started all this work to correct this very problem and I have accomplished nothing!!! The wires,points,cond,everything is new. The coils test exactly the same. There are two magnets in my F/W. Any more help out there?

 

[AlTn]

Re: no spark on one cylinder

Re: no spark on one cylinder

Bare..looking at parts diagram for a magneto for 1974, 25 hp. evinrude <model no. 25E74M >..it indicates you have 2 sets of points, 2 condensors and 1 charge coil under the f/w, with 2 external coils...is your's the older universal magneto setup?

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

Yes sir, mine has two coils under the F/W just like a 72R20 that I have. It does show the diagram like you said but I guess mine is the old design.

 

[AlTn]

Re: no spark on one cylinder

Re: no spark on one cylinder

as others have said..clean the points with solvent < acetone works well > then check the position of the coil heels over the bosses and make certain that they are exactly even with the bosses..if you'll google..bringing a 1956 johnson 15 hp. back to life...parts 4 and 5 discuss your ignition set up

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

Is it possible for the F/W magnets to go bad or get weak?

 

[tx1961whaler]

Re: no spark on one cylinder

Re: no spark on one cylinder

I started all this work to correct this very problem and I have accomplished nothing!!! The wires,points,cond,everything is new. The coils test exactly the same. There are two magnets in my F/W. Any more help out there?

Getting po'd at me ain't helping your motor out. What is disturbing is that you are describing a pre-1974 universal magneto and possibly a later model flywheel? Are there two sets of magnets 180 deg. apart, or just one set on one side?

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

Don't be so defenseive the remark was aimed at me. I aprreciate all the help. 2 magnets 180 apart is correct.

 

[tx1961whaler]

Re: no spark on one cylinder

Re: no spark on one cylinder

Don't be so defenseive the remark was aimed at me. I aprreciate all the help. 2 magnets 180 apart is correct.

That seems wrong for a universal magneto (2-coil) ignition. They usually have one flywheel magnet that fires off each coil once per revolution. The ones with the single charge coil and two external coils have the 2 magnet flywheel.
Is this a new-to-you motor?

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

Sorry if I offended anyone. I am just disgusted with myself for being a parts changer, instead of me actually diagnosing the real problem before I started working on the motor. I should have come here first, but all the parts mentioned were looking bad so no harm I guess. There looks like two magnets on each side 180 apart with a total of 4 magnets. It looks like at some point the coils came into contact with the F/W and scored it.

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

Would pictures be of any help?

 

[Daviet]

Re: no spark on one cylinder

Re: no spark on one cylinder

Have we determined exactly what engine we are working on?

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

The tag says 25E74M. The engine looks identical to a 72 model 20hp Johnson that I have.

 

[tx1961whaler]

Re: no spark on one cylinder

Re: no spark on one cylinder

Sounds weird, but can you look at the 1972 flywheel and see if it looks like the one on the 25E74M? This whole 2 magnet thing has me twisted. The 1972 and 1974 flywheels have different part numbers.

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

The 20 is at the lake now so I can't look at it, but there is a # on the bottom of the 25 f/w that is 581105.

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

View attachment 109390View attachment 109391
Hope you can see the pics, never done this before

 

[bare3176]

Re: no spark on one cylinder

Re: no spark on one cylinder

I did some research and see what ya'll are talking about. It should have basicly three coils. So something was changed at some point, but the motor was running fine with this setup. Does everything look right and should the f/w have two magnets or one? All the inside stuff looks pre-72.