1975 25 hp evinrude 25502B

[KC9000]

I have this project. 1975 25 hp evinrude.
120 compression both cylinders.
I have to have it 1/4 inch past armature marks to start it. I have tried the needle setting at 1 1/2 all the way to 3 turns out. Turning and waiting 1/8 inch at a time.
Will not start with carb flap closed in lowest throttle setting.
I put new coils, new condensers, I have cleaned points and gapped them. I changed pump diaphram and gaskets. It has a small gas line going from pump to carb. Going to get a 1/4 inch regular line.
This thing seems like its running on top cylinder. Pull bottom plug boot with it running and does not die barley makes a difference. Pull top plug boot while running and it dies and will shock me if im touching motor. I am starting to think I have a bare wire somewhere. Any advise would be greatly appreciated. Got the carb apart and it is not clogged. Cleaning it up and will try again.

 

[jimmbo]

Try a new properly gapped Spark Plug in the Top Cylinder. Check the Boot for cracks that provide an opening for the Current to travel along the Plug Insulator to ground
Verify that both Cylinders are getting a Spark that can jump a 5/16" gap

 

[Crosbyman]

what ohms value do you see testing from plug boots to engine frame... post reseults!!

 

[KC9000]

Top - 6.88k
Bottom - 6.68k
I forgot to mention I installed new champion J4C spark plugs gapped at .030 with feeler gauge. Pulled those and they are getting fuel and looks very even. I also tested with stop button removed with same issues. I feel like the old ignition wires from magneto have finally went bad? Maybe pinched / broken under the magneto wire run? I will pull it today after testing after light cleaning of the carb.

 

[Crosbyman]

well that is good. HV side anyway being new coils and all

Make certain the coil's "pulse wire" from the magneto has continuity see diagram most likely like your wiring.

https://maxrules.com/graphics/omc/wiring/1973-76_18-25.jpg

if similar make certain that the "suspect coil" ... kill "extended wire" to the switch if remote start or simple kill push switch if rope start ....is not chaffed and grounded anywhere in running mode the 2 kill wires posts and wires must not be interconnected or grounded anywhere otherwise the coil won't fire.

 

[airshot]

On most motors the start position on the throttle is at a fast idle position, not dead slow unless engine is still warm from a prior run. Sounds like you have other issues, but....your start position needs to be a little faster on the throttle position when cold with choke in proper position.

 

[saltchuckmatt]

I have this project. 1975 25 hp evinrude.
120 compression both cylinders.
I have to have it 1/4 inch past armature marks to start it. I have tried the needle setting at 1 1/2 all the way to 3 turns out. Turning and waiting 1/8 inch at a time.
Will not start with carb flap closed in lowest throttle setting.
I put new coils, new condensers, I have cleaned points and gapped them. I changed pump diaphram and gaskets. It has a small gas line going from pump to carb. Going to get a 1/4 inch regular line.
This thing seems like its running on top cylinder. Pull bottom plug boot with it running and does not die barley makes a difference. Pull top plug boot while running and it dies and will shock me if im touching motor. I am starting to think I have a bare wire somewhere. Any advise would be greatly appreciated. Got the carb apart and it is not clogged. Cleaning it up and will try again.

Tiller or remote motor?

5/16 gap like suggested? Yes or no?

GAP testers are inexpensive.

1/8 inch turns or 1/8 of a turn?

Spark has to advance to start cold.

I've been hit myself....motor harness was the culprit.

Is there fiber washers between the ignition coil and powerhead?

 

[KC9000]

Tiller and pull rope
Will test and post the 5/16 gap
1/8 turn on rich / lean adjustment
No fiber washer between coil and powerhead. Coil ground wire Between coil and powerhead. No washer separating those.

As a test. I am going to put some new wire from magneto to coil to see it those wires are to blame. I will test spark gap first.

 

[flyingscott]

Points and condensers need to be checked.

 

[saltchuckmatt]

Tiller and pull rope
Will test and post the 5/16 gap
1/8 turn on rich / lean adjustment
No fiber washer between coil and powerhead. Coil ground wire Between coil and powerhead. No washer separating those.

As a test. I am going to put some new wire from magneto to coil to see it those wires are to blame. I will test spark gap first.

Pull it at night...might see flashes.
If you got hit, something zapping. You might have two shorts or two problems.

Again, wiring is suspect...old and if it got hot once, insulation melts. Seen it more than once.

 

[KC9000]

Ok so found the issue. Thank you guys for the advice you all are in the right spot. Tested bottom coil spark it jumped 5/16 and shocked me. I decided to throw some electrical tape on my new cheap ass coils plug boot. It stopped leaking spark and she is idling like a dream. I cleaned the carb as well.
I pulled flywheel clean point set gap and changed condensers. Tested old ones and they bench tested good. Did this before the tape. Was not the issue.

 

[Crosbyman]

great news thanks for the feedback ... one down.. thousands to go

 

[KC9000]

Yes. Forsure. My client will be happy. You guys are the best!!! Thanks again. I am always grateful for this site and all the great advice!! Thank you everyone.