1989 Mercury 25hp electrical schematic

[F-16 Falcon]

Hi folks, Here?s my very first post. I am helping my son out by getting his outboard running. It died running down the river and wouldn't restart. It's also been sitting for about 1 1/2 years now due to war (he?s military) and the distance between us. Anyway, I now have the boat at my house so I'm just now getting started on it. Here's what I've figured out so far. I verified there is spark going to both plugs. Today I plan to pull the plugs and see if they are gapped correctly and also check compression. What is the correct gap for the spark plugs on this motor? If compression checks out ok then I want to ring out what is presumably an on/off switch on the side of the motor? And then determine if also has an emergency kill circuit, and if so, where its located? This is partly why I need to see the electrical schematic. If someone can provide it I would most certainly appreciate it. Thank you very much in advance!

 

[carholme]

Re: 1989 Mercury 25hp electrical schematic

Falcon;

Do you have a s/n for the engine?

Gerry

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

I can get it later on this evening if you don't mind waiting and also telling me where on the engine to look for it. I assume it would be somewhere on the head? Sorry, I've never worked on any 2 stoke outboards before.:redface:

Thanks!

 

[carholme]

Re: 1989 Mercury 25hp electrical schematic

Falcon:

http://www.iboats.com/basics/serial_number_year.html

or between the transom clamps, you may notice a data plate, or

on the powerhead, you will see a disc like this:

http://img84.imageshack.us/img84/8224/391496208.jpg

I'll check back later when you post it.

Gerry

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Here you go and Thank You very much.

0A964464

 

[carholme]

Re: 1989 Mercury 25hp electrical schematic

Falcon;

That s/n comes up as;

25 25XD 2-cyl 0A911346 0B114230 1986 USA

From here:

http://www.marinshopen.se/Motorer/O...Mercury2takt2cyl1825hp/tabid/483/Default.aspx

It is a model:

1025206 MERCURY 1986 25

Parts listing:

http://www.crowleymarine.com/mercury-outboard/274.cfm

Unfortunately, as it came up as an '86 rather than an '89, I cannot get you the online service manual which contains the wiring diagrams.

I will see if I can dig one up elsewhere.

Hope your son is well and that he is home soon and safe.

Gerry

 

[windy5849]

Re: 1989 Mercury 25hp electrical schematic

If you have spark at the plugs,I'm not sure why you need this,but I scanned the page from my 1990 25hp manual.I hope it is similar enough to help you.Our prayers are with your son.

http://s1227.photobucket.com/albums/ee427/windy584/?action=view&current=199025hpMerc.jpg

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Thank You Gerry. My son bought the engine, the boat, and the trailer from a large dealer about two years ago and the dealer said it was an 89. Anyway, I'll check title and see what it says...The reason for the schematic is because I'm not familiar outboards or any of their wiring and I want to ring out all of it point to point while inspecting each one for damage from end to end.

Last night I remove the plugs to inspect them and to perform compression and found out these plugs don't require any gapping, they don't even the have dog ears on them. I never seen this before. I also found out the starter want rotate even if the selenoid is by- passed. Since I like the idea of electric start, I'm thinking about tearing it apart and trying to figure out what's wrong with it. If I do, are all of the compoents available on-line or at a dealer?

Last thing, when I picked up the boat at son's house I found out the the tank was full of fuel and water and also had a big split in the tank (possibly cracked from water). Anyway, I through out the tank/hoseand bought new stuff from wal-mart. I haven't tried filling it up and cranking on it yet. Before I do that I was thinking I should spray something into the carb and heads. Should I, and if so what would you recommend I use?

Gary

 

[carholme]

Re: 1989 Mercury 25hp electrical schematic

Gary;

Sorry to be late getting back.


If you refer to the parts listing which I sent you, under IGNITION COMPONENTS, item 16, you will see that you have the correct type of surface gap sparkplugs. If you click on the picture of the plug, about 2/3of the way down the page, you can blow it up for a better look.

Just about everything you require for normal service of the engine is available as you will see in the parts list and can be purchased from Iboats or other sites. Many times you will see the part listed as NLA (No longer available) but a quick search online usually brings them up somewhere.

It sounds as though your engine has sat in the elements for quite some time. Before you attempt to start it, you should get a spray of fuel/oil mix into the plug holes and let it sit overnight and then gently ease the flywheel back and forth (or pull gently if manual start, to slowly rotate the flywheel) a bit to free up anything which may be corroded or stuck, then give the flywheel a few rotations.

Depending on how long it has sat, you have to give serious thought to changing the waterpump impeller and lower unit oil as well as seals on the drain and fill valves, cleaning the fuel filter, carb bowls (possible carb teardown and repair kit)

Many thanks to windy for supplying the schematic.

The service manual for this engine is p/n 90-43509--3

http://cgi.ebay.com/ebaymotors/MERC-MARINER-18-20-25-OUTBOARD-SERVICE-MANUAL-/390301564066

Gerry

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Ok I'll sum up my questions with hope of someone helping me.

1) I thought all spark plugs were basiclly the same but with these there is no way to adjust the gap, whatthe heck? I've read other post where folks are setting the gap on there plugs. Is this something unique to 2 strokes?

2) I think this engine might have had water mixed with fuel plus it sat in the weather for about a year. I'm fearful of rust so want to take every precautionto make sure I don't foul up the cylinders if it does fire up. What precautions should I take?

3) the starter will not spin so I can't get good compression Readings. The tester I'm using doesn't hold pressure I because it bleeds all of the Air out of it's valve. I've used it on v8,s before but i was cranking turning the engine with the starter. When I pull on the cord it pumps up but bleeds down immidialy, how do I check compression without a starter?

4) since I suspect the fuel tank had water in it should I remove and clean the carb?

Please help. Thanks

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Thanks a bunch Gerry. You've been very helful and kind. If I have more questions I'll start a new thread. Plan is to to have his boat ready for fishing when he comes home from afgan on leave in about 6 weeks.

 

[carholme]

Re: 1989 Mercury 25hp electrical schematic

Gary;

Six weeks is not too long away and I am sure there will be many people on here who will want to get it up and running for you. Don't worry about starting another thread as it helps to keep your history contained without having to search all over the forum. I am excited for you and your family and wish you success.

Gerry

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

:facepalm:

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Ok I removed the starter, took it apart and the motor windings smell like burnt wire. Also the brushes are worn. I think I'm gonna just buy another one. Next I removed the carb. Wow..it's pitiful. Don't see how fuel could have made it through it. Gonna tear it apart clean and reassemble. All the gaskets look good so I'm gonna re-use them. Anybody Forsee a problem with that?

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Ok I cleaned up the carb real good reinstalled and finally got it to crank and run but only on the bottom cylinder. When I pulled the top plug it was dry. I also notice fuel coming out from between the intake and head (bubbling out). I did start it back up to check the top cylinder for spark, it had spark but I'm not sure if it's enough. Don't have DVA meter.

I finally got frustrated, quit and had a couple of cold refreshments. I wondered back out to the boat scratching my head and realized fuel was pouring out of the carb and all over the ground. I quickly reliefed the pressure off the fuel tank and it quit leaking. Still scratching my head.

Gary

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Oh yeah, it was hard to crank and wouldn't idle. Had to give it throttle to keep it running.

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

This morning when I get to work I pulled up the pictoral for the carb I then realized I may have installed the float on the shaft backwards whenever I put the carb back together. Guess I'll reverse it when I get home today and try it again. I'm still scratching my head as to why it was only running on the bottom cylinder and the top cylinder plug appeared dry to me. I hope I didn't screw that cylinder by running it dry.

 

[F-16 Falcon]

Re: 1989 Mercury 25hp electrical schematic

Gary;

Six weeks is not too long away and I am sure there will be many people on here who will want to get it up and running for you. Don't worry about starting another thread as it helps to keep your history contained without having to search all over the forum. I am excited for you and your family and wish you success.

Gerry

Gerry, she's purring like a kitten now and ready to go as soon as son arrives. I haven't had time to update the status tell you many Thanks for steering me in right direction. Gary

 

[carholme]

Re: 1989 Mercury 25hp electrical schematic

Gary;

Wondered where you went but I have been busy as well. Glad you have her up and running. Not long to go now, hope all works out and that you have a great time when boyo gets home. All the best.

Gerry