Motor rewire

[aburke120]

I have purchased a 1990 sea nymph ss195 with a non running 1975 850 mercury outboard, sn 429,xxx the motor will turn over, but
does not fire. Removing the cowl, I found a rats nest of repairs done to almost every wire I could see, splices, solder joints
plastic tape, broken wires, I'll put a pic at the end. The plug has broken wires also. I'm not afraid to tackle something like
this I worked as an electrician for 40 years in an iron foundry, and what I found wasn't anything I hadn't seen before. there's
only 7 wires on the plug, 2 being positive and negative from the battery, the rest need to be found on a print.
I don't know a lot about outboard motors, but I'm going to give it a try. I may have jumpers where they shouldn't be but
I should be able to make this motor run, as long as some of the parts aren't bad.
Parts on the motor are a challenge also, I'm looking for a "choke solenoid" I'm thinking it's up towards the top of the motor
and has a small metal cable coming out of the bottom. supposed to have a grey wire on it, but all the wires are black. I will
continue this as I find and learn about outboard motor wiring. Later..........................Al

 

[Chris1956]

Wiring diagram is found at maxrules web site. A 1975 850 should have 1 coil and battery powered CDI ignition. A 1976 850 will have 4 coils and ADI ignition.

You can order a new engine wiring harness off the web. Look for a good price.

 

[aburke120]

what type and size wire is used on a new engine wiring harness

 

[Chris1956]

Ideally wire should be marine grade (tinned and fine strand). Most of the wires would be 12 or 14 AWG, I would expect.

 

[Faztbullet]

Don't spend a dime on it till you jump starter and test compression!!!!! Then jump ignition and see it it has spark.. This motor with problems can get very deep in the billfold!!!

 

[aburke120]

ran a compression test before I bought it, and knew that it didn't have spark then. How do I jump the ignition. Thanks.

 

[aburke120]

As I'm rewiring this motor I'm looking for a choke solenoid, the book says that the choke solenoid has a green wire on it, all the wires coming from what's left of the engine harness are black, and most are broken. The black wire that I think is supposed to be green runs to the top of the engine near the fly wheel, is this where the choke solenoid is located? thanks.

 

[Chris1956]

The choke solenoid is directly above the center of the carbs. The wire should be grey.

 

[Chris1956]

Do yourself a favor. Jumper the ignition and test her for spark. If she has spark, by a new wiring harness.

Using some jumper wires, connect a battery...neg post to engine frame and positive to red on switchbox. Jumper red on switchbox to adjacent white terminal on switchbox. Make sure green terminal on switchbox is connected to coil, and other side of coil is grounded. Put a wire into colt "tower" and hold near ground.

Jumper Brown and other white terminal on switchbox (dist.side) together, and using jumper wire on black switchbox terminal, touch to ground. Each touch of ground should fire coil.


Check CDI Ignition troubleshooting guide page 67, for more detail and illustration.

 

[merc850]

If it is a 1975 here's a wiring diagram; (the coil and starter solenoid are physically different and in different locations), the distributor should have a ground wire from the housing to the block. I would buy a new harness and do it right, or you might have it catch fire or leave you stranded.

 

[aburke120]

Thanks merc850, that's the diagram I've been following. thanks chris1956 I found the choke solenoid, it only has one place to put a terminal, and the wire that's on it will only read to ground with a VOM. There is another wire on the choke linkage between the carbs, that wire won't read to ground or back to the plug. another thing I found is on top of the switch box area is a manual choke knob. There's nothing attached to it except a wire that looks like it was spliced at one time. Thanks for all the help, I'm going to get a newer harness, but I enjoy playing with this motor, and it's wiring issues.

 

[aburke120]

Chris1956, not sure what this means. " Put a wire into colt "tower" and hold near ground." starting to get cold here in michigan, limiting my time outdoors working on this motor. Don't have coils, this motor has a distributor.

 

[Chris1956]

Gee, I thought an electrician would know the slang term for a ign coil secondary winding....Your coil is likely orange and mounted under the distributor. Wires screw into the distributor cap. The rotor is not removable and fragile. A new Dist cap (hardly ever needed) is $100+. Rotor is $200+.

Merc used a insulated wire with ring terminals from the manual choke knob to the choke plate, instead of a cord or cable. It will not have any continuity.

Your motor needs to have separate ground cables from the distributor to the block and the starter to the block, for them to function, as they are mounted in rubber.

 

[aburke120]

Chris thanks, the wire that's on the choke coil, Is there only one wire supposed to be on it? I see on the wiring diagram that the choke coil has a cowl ground. Is that like a chassis ground on a car, or a seperate ground.

 

[Chris1956]

The choke solenoid is grounded to the upper cowling support. There are ground wires from the block to the lower cowling support, at the base of the powerhead. The main ground (negative battery cable), is bolted to the lower cowling support.

 

[aburke120]

I saw today that there is a ground on the upper cowling support. still concerned with the choke solenoid reading to ground. I also found where the wire from the manual choke is located, like everything else under the hood, the splice was broken. Had to quit for today, 42 degrees in the sun isn't too bad, but when the sun went down it got cold, thanks again for the help.

 

[aburke120]

got wires spliced at the plug, and rerouted hopefully to where they belong. Got a battery charging tonight and will put the juice to it in the morning and see if it will spin and spark.

 

[merc850]

The choke solenoid should read .67 - .79 ohms, how's the wiring in the control box it might be rotten too.

 

[aburke120]

In the control box? everything going to it I changed, what's "inside"

 

[Chris1956]

Normally the MerControl would have the ign switch, choke solenoid and neutral interlock switch. These usually last longer than the motor harness.