Logo
FULL SITE MENU

Mariner 20HP S/N

S

Sammy728

New member
This looks like a regular Mariner outboard. I cannot match the S/N.
The 653 is a painted part of the plate & the rest is stamped.
Also, If the S/N doesn't match anything, how do I order parts?
Any help?
 
The 653 makes it a 1974 to 1979 Yamaha built (for Merc) "A" model Mariner which was mechanically identical to a 1972 Yamaha model P400A (which later became the model 20A and last saw production in 1978).

As to parts - I have no idea - Merc does not even have a parts list anymore for this model and I have never seen a Yamaha parts list going that far back.
 
We bought this a few years ago from a guy who had it in his attic for years. Never idled great. Last year used it more(a few times a week). At start of year it was fouling plugs. By end of year only running on one cylinder. I was told points may be bad. Pulled flywheel, look good, check good on ohmmeter. Is there a way to check coil packs? Any other ideas?
 
To check the coils under the flywheel (resistance checks), you first need to remove the flywheel.

There should be a Gray lead and an Orange lead. Set your ohm meter to x1 ohms. Red probe goes to EITHER the gray or orange lead, black probe goes to one of the screws holding the coils down to the mounting plate (and then test the second lead).

Resistance should be between 1.5 and 1.9 ohms.

To test the coils that feed the sparkplugs, disconnect their leads and put the red probe on the side where either the orange or grey wire was connected and the black on the side that had the black wire connected.

The resistance here should be between 1.35 and 1.65 ohms.

You can do one final test. Hook everything back where it belongs but don't reinstall the flywheel.

Set your ohm meter to 1K and put the red probe into the sparkplug wire (the end that would go on the sparkplug) and the black probe on one of the coil mounting screws under the flywheel - you should get 5.44-6.65 K-Ohms at this location.
 
Sorry I took so long. I was working 7 days x 13 hrs. I slowed down again & my son wants his motor.
Just to make sure we are on the same page: One set of points has 2 orange & 1 green wire. The other set has 2 grey & 1 green. On either set 1 goes to the front magneto(coil), 1 goes to the coil pack(plug), And the green goes to the condenser. The rear magneto wires connect to nothing. I assume that is for an optional charging system.
My ohmmeter is different. It has 200, 2000, 20k, 200k, & 2000k. No x1 but 200 seems to be the most accurate. It jumps between 1.6 & 1.7 off grey or orange. The coilpacks(plug coil) only have one wire(orange or grey) from the points and a plug wire on the other side. There is a ground wire from the #1 coilpack bolt to a ground under the flywheel. I assume that replaces the wires & the negative is just ground. I checked from the lead to
the bolt hole. It was 2.1 on both. That's not right but they can't both be bad but still read the same, can they?
Even more interesting: I took #1 coilpack off. Both bolt holes are copper. Probably for grounding. If I check the hole where the ground wire was it is at 2.1, but the other hole reads 4.2 even if I sand it. Bad ground? That should not matter though because I have one good ground? On the final check I put the ohmmeter on 20k to get a reading. I got 6.77 on #1 and 6.66 on #2. Again, I apologize for the delay, but I really want to figure this out. Thanks.
 
I am new to these forums. I was looking for help on an outboard, which I know very little about. I know enough about car engines to get me in trouble. I took it to a local marina. He told me he would have to go through the whole engine and it would cost more than it was worth. He also said he cannot buy the new parts it will need.
He suggested the internet because I might find used or new old stock parts that he refused to use. So I found this site and asked a couple questions. A knowledgable member asked me to run a few tests. I did my best to answer his questions, but I think I somehow pissed him off. For that I sincerely appologize. I was hoping someone could read my post and let me know if they had any ideas. I would appreciate it very much, Thank you.
 
I doubt if you pissed Graham off,he just missed your post.Have you any spark on any coil? If so swap with coil with no spark and if problem moves your coil is gone.That is the only way I know how to do it,not been edumacated,:D.
If you have no spark at all,check your kill and tilt switches.
If they check out,try borrow a known good coil and go through the test run and if you still have no spark I think it may be your switch box
 
Disregard last,I reread about points,not a 100% sure about those.But you should have continuity between two points on a ground
 
Yes, sorry, I think your post got lost in my mountain of other threads. Besides this board, which keeps me busy, I also write on a boat builders website (for wood boat builders) and get upwards of two dozen private emails a day with boat/motor related questions, and in between I actually have to do some "real work" - so sometimes I get a little lost :)

And your numbers look ok - you note only the single wire to the (spark) coils and that is the way it was designed (no secondaries on these).

The 2.1 reading you get on both (between primary and ground) could simply be because the coils are cold. So I am not overly concerned with that - if you want to satisfy yourself, heat them up a bit with a blow dryer or heat gun (just not too hot) and the resistance should drop down into range.

And ditto for your final check - close enough that I think it's simply the cold components giving you the extra resistance.

So if your points are gapped properly and otherwise functioning well, it looks like your ignition is ok...
 
Back
Top