78 model 200, 20 hp mercury not firing

[wylie catter]

I bought another small outboard yesterday in non running condition. It was supposedly running good when it was stored about 8 years ago. The compression is 120 on both cylinders and it looks to be in good overall condition.

So today I grounded new spark plugs out on the block and could not get any fire on either cylinder.

Where should I start? How do I check the stator, trigger or whatever I might need to check?

I really appreciate any help here fellas.

 

[SparkieBoat]

Re: 78 model 200, 20 hp mercury not firing

get a DVA adapter and a multi meter if you do not already have one. http://www.usatoolwarehouse.com/usat...e/ESI-640.html
$25 + shipping and worth every penny..if you are going to be a DIYer you also need spark gap tester and engine compression gauge and inductive timing light..along with a good socket and Wrench set also get a good pair of Long needle nose pliers and a flywheel puller..and you are in business..all cheap tools..try Harbor Freight. ( I do prefer higher quality wrenches and socket sets, not the cheapo ones.) go to CDI electronics web site for trouble shooting guide....

 

[James Jacksonville fla]

Re: 78 model 200, 20 hp mercury not firing

i owned a merc of simmalar year76 those are great motors when they run! the wiring can get screwed sometimes by weather and saltwater. does it have a black plastic box mounted on the side of it? with wires comming out??? if so thats the brain? or whatever mine had frayed wires and i had to buy a new one hundred bucks! but after that it worked the spark/power goes from the stator to the box then the coils then the plugs i think?. the box is sealed but years can wear that stuff away on mine the wires rotted inside the insulation due to electrolosis chase the spark down and find out if your getting electricity. good luck man i loved and hated that old 20 hp mercury

 

[wylie catter]

Re: 78 model 200, 20 hp mercury not firing

Yeah it has the box on the side. I'm with you on the love hate. I had a 73 a few years ago. When they run they have crazy power for a 20. But they weigh about a 100 pounds and its like trying to pull start a truck motor.

I'm gonna try to back track the spark as soon as I can get a volunteer puller.

 

[James Jacksonville fla]

Re: 78 model 200, 20 hp mercury not firing

lol!!! If you find one of those ill give him a full time gig!!!! I know you prob know this but..... if that puller is hard to pull it means that thier is no fire in the combustion chamber as you already know. as soon as you get a spark it is much easier to pull. you have that to look forward to? lol!

 

[ONERCBOATER]

Re: 78 model 200, 20 hp mercury not firing

my 1st advice (i have that version with electric start) is that you look ever so carefully at the wires... make sure the insulation is intact.... mine the insulation was flat out trashed (as in the insulation degraded and stuck to what ever it was next to...or just fell off, sometimes was good except where you couldnt see it)'...rewired her and she worked well. second thought is that if the wires appear ok, that you loosen and then tighten all the wire connectors, where the wires are screwed to components and buses and what not (when the wire has a connector that screws down)...sometimes oxidation will start there that isn't readily visible and though the connection looks good it does not conduct until it is loosened and retightened.... my 1976 merc 200 did that to me i got even though it donated parts to my 1978 merc 200 that now purrs.
Heat shrink tubing and a soldering gun may become your new best friend in the near future.

"but after that it worked the spark/power goes from the stator to the box then the coils then the plugs i think?"-----James Jacksonville fla
that is the path that i saw as well, and yes electrolysis, heat, age, oxidation all combine to destroy either the wires or the insulation or both.

however i must say that working on the lil engine was well worth it, very nice engine in the end, i think you will be happy.

Sean

 

[wylie catter]

Re: 78 model 200, 20 hp mercury not firing

Well I done some tracking using a volt meter and some rubber clamps to hold the elctrodes in place. I am getting power to both coils when its pulled. I can't say how much exactly because it would jump up on the display for half a second. But they both deffenetly have some power coming to them. And none at all coming out the plug wires. I didn't think about loosening and cleaning all the connections. That's a great idea. All my wiring looks to be excellent. I hope its bad connections.

 

[ONERCBOATER]

Re: 78 model 200, 20 hp mercury not firing

sometimes it is the lil things... i hope it is the connections too, would be cheaper and less of a headache.

 

[wylie catter]

Re: 78 model 200, 20 hp mercury not firing

Cleaned the connections. Still no power at all coming out of either coil. I wonder where's the cheapest place to order coils?

 

[mc66]

Re: 78 model 200, 20 hp mercury not firing

i have same motor 1978 20 (200) merc no spark brown and white wires out of cdi box (merc switch) go from 16 gauge wire to 20 gauge wire butt conectiors rotted off cut added new connectors fired up 1 hour ago even got nice shock. take out both plugs and ground easy to pull and check yourself

 

[wylie catter]

Re: 78 model 200, 20 hp mercury not firing

I'll chech those, thanks for the input. I was talking to another man yesterday and he said the same thing happened to him and it was the box. He said he was getting fire to both coils but just didn't believe that both coils would go bad at the same time. So he replaced the box and it fired right up.

I'm going to chech those wires. I still think it's something simple like that. Thanks.

 

[wylie catter]

Re: 78 model 200, 20 hp mercury not firing

Yall were right! I just went and pulled the cdi box off and immediatly saw a problem. One of the wires (brown I think) is shot. The insulation is falling off like paper and the remaining copper wires are frazzled, thin and few. Probably only about 10 single strands still connected. I guess that's how I was getting the little bit of fire to the coils.

I should have took the advice better than I did. I could have diagnosed this several days ago. And I still havent looked at every wire. There's some up around the stator that I cant see. I'm going to get a visual on them too.

Man, I'm glad I haven't ordered any coils yet. Yall know your stuff, and I'm really appreciative of your time.

 

[boomer2001]

Re: 78 model 200, 20 hp mercury not firing

i have same motor 1978 20 (200) merc no spark brown and white wires out of cdi box (merc switch) go from 16 gauge wire to 20 gauge wire butt conectiors rotted off cut added new connectors fired up 1 hour ago even got nice shock. take out both plugs and ground easy to pull and check yourself

Can someone send me a pic of were the wires go? I bought a 200-20 and the switch box was not wired up. he had replaced it for forgot how and were wires went. I would really appreciate it greatly. Thanks boomer (medisport2001@msn.com)

 

[johnson20]

Re: 78 model 200, 20 hp mercury not firing

I had a 40 mercury 1976 same system and it was the wires going to stator... they looked not bad till I cut them short and ohm meter tested it. If no fire after cdi fix look at stator wires.

Just like yours stored for a long time.

guy bought a new computer before i took a chance and payed 400 for it.

Ran like new

 

[wylie catter]

Re: 78 model 200, 20 hp mercury not firing

Can someone send me a pic of were the wires go? I bought a 200-20 and the switch box was not wired up. he had replaced it for forgot how and were wires went. I would really appreciate it greatly. Thanks boomer (medisport2001@msn.com)

I believe there is a brown and white wire that go to brown and white. There is a black wire about 4" long that grounds to the bracket the box mounts to. There is a longer wire, yellow or orange I think, it goes under the rear of the flywheel and is screwed down with 2 other wires near the bottom of the flywheel on the port side of the block. And then I think each coil gets a striped and unstriped wire of the same color.

 

[wylie catter]

Re: 78 model 200, 20 hp mercury not firing

Got a new cdi box from a place in georgia online, delivered and all for 175. Put it on and it fires great. Got it to crank after cleaning the carb. But no water pumping at all. So I pulled the foot and the impeller is shot. So now a complete water pump kit is ordered.

Slow, expensive progress, I hope it ends up being worth it. I think it will.