Merc ignition works fine amp frequently dead next day

"Engine: 1980 115hp Mercury ou

"Engine: 1980 115hp Mercury outboard w/quicksilver control box

Order of events:
Friday: Ran the boat on and off all day, ignition perfect, engine ran
fine.

Saturday morning: Connected boat running lights, cigarette lighter
(were previously unconnected). When testing the cigarette lighter, in
line fuse (from 12V +) blew. As a side note, I hadn't known which
terminal was or - on the lighter, and had them connected in reverse.
The engine ignition leads *had* been connected during this test.

Saturday afternoon: Went to take the boat for a spin. Turned the key,
cranked normally for about two seconds, let key go. Turned key again
w/choke. Completely dead from that point on, w/ no clicking from the
solenoid.

Charged the battery for 12 hours, still no good. Tried a new battery,
still no good. Then:

I followed the instructions in the Seloc Mercury Outboard Tune-up and
Repair Manual (1965 - 1986):

1. Ignition switch (wiring harness test). I did this test with 1 $15
multi range tester (incuding an XK1 setting).
a. Connected pin 7 & pin 4 to ohmmeter, with key OFF. Manual says
should be continuity, but no ohmmeter reading.
b. Connected pin 1 & pin 3 to ohmmeter, key in RUN/START. Manual
says should be continuity, but no ohmmeter reading.

Ironically, when I try this with a simple filament tester by running
12VDC through the pins, a. 7 & 4 light up, but only when key is in
RUN/START. 1 & 3 do not light under any circumstances. Visibly,
ignition switch and solder connections on it seem to be fine. Don't
know what to make of procedure in manual and/or the multitester I'm
using.

2. Performed all the ignition tests listed in the cranking circuit
chapter (noting that my multirange tester gets an 11V reading from the
+ terminal on the solenoid, with - on the bottom of the starter):
a. Cranking Motor Solenoid test: small yellow/red connection to
solenoid common ground, key in START. No reading, good.
b. Neutral Start Switch: Common ground yellow wire connection on
ignition switch (assuming this switch is in the control box), key in
START. No reading, good.
c. Ignition Switch: Same as in b., but red wire connection, key
OFF. No reading, good.
d. Further tests for solenoid: Large yellow wire connection on
solenoid (goes to + on starter) to common ground, key in START. No
reading. According to manual, this means solenoid is defective. I
buy a new one.

Again, the multirange tester does get a reading from the + and -
battery leads.

Also checked inline fuse in red wire going to solenoid, was fine.

The starter itself is fine; if I bypass the solenoid with battery +
and - directly to it, it cranks.

Also, both old and new solenoid pass standalone solenoid test in
manual (+ and -) directly to small connections; solenoid clicks loud.

I replace the solenoid with the new one. After installing new one, no
change in behavior, no clicking with key in START.

Can anyone offer suggestions here? According to the manual, the
rectifier can get fried during situations like the one I described
with the cigarette ligher connection- but I noticed another message on
this board saying that the rectifier has nothing to do with starting,
only recharging the battery.

Thanks in advance,
Joe"

" Joe,

Swapping the ne

" Joe,

Swapping the negative and postive on 99% of devices on a DC system will have no effect, other than a loss of performance. Anything with circuitry, such as VHF radios, depth finder etc.. possibly could be damaged, but lights, speakers, and cigarette lighters will work the same either way. I think pumps work either way, but just don't perform quite right. What would be BAD is if you attempted to charge the battery through a cigarette lighter that was wired backwards or if you ran something off the lighter that needed correct wiring (ie cell phone charger). So.. what I'm saying is that it's a BAD idea to wire anything backwards, but it should not cause a fuse to blow, you must have another problem... there is an off chance if you have a metal boat that it is grounded for some reason and the cigarette lighter managed to cause a short because it is metal and was mounted to a metal surface.

I have a very similar engine, and have that seloc manual you are speaking of, but not in front of me; the first thing I would try is manually jumping the starter solenoid. Figure out what lead(s) need to be + (or - if that's the case) for it to route power to the starter and jump them. If the starter kicks on, you have just eliminated everything in the engine. Then, it's just the controls and harness, and that should be fairly simple to figure out.

One thing I'm wondering as well is how you are supplying power to the cigarette lighter and other devices. Either the cigarette lighter thing and the starting problem are not related, or you are using one of the leads in the wiring harness or control box as a way to supply power.. if the later is the case, this is another BAD idea. The only thing that should ever recieve power from the wiring harness/control box, other than engine components, is a solenoid.

My .02, hope it helps, tell us how things are working out,

Jon "

" Just a thought, and I do not

" Just a thought, and I do not know if this engine has one, kill switch?? "

" Jeremy: I only wish it were

" Jeremy: I only wish it were so, but this was the first thing I looked at.

Jon: Thanks very much for your response. As it turns out, I have a pretty standard setup; no funky electrical connections. It's a 16ft 66' fiberglass Chris Craft only rated for 100hp, actually. The harness/control box/tachometer have their own circuit, w/no other add-ons. On the plus side, the running lights and cigarette lighter work perfectly now ;-)

It's good to know that I couldn't have caused serious damage by having polarity reversed. However, I haven't tried applying 12VDC directly to the solenoid connections while installed and hooked up to the starter because I'm hardly even a novice with electricity, and don't know if it could do damage to other components (can it?). I only know it has four connections: the smaller 'S' and 'I' connections (one of them is a ground), and two large connections (+ from the battery and yellow/red from the harness).

My first goal has been to determine whether the harness/control box circuit is at fault, or something within the engine, and if it was safe to apply juice to the solenoid while installed as you mentioned, I would do so (is it?). Is there a way to simulate a closed circuit, in other words key in START, from the control box just by connecting the (female) connection(s) within the harness plug?

How likely is it that the ignition switch circuit can go kaput just like that, especially after working fine for a day?

Joe "

"Joe,

Jon is correct when

"Joe,

Jon is correct when he suggests that you go directly to the solenoid. Take a piece of wire. Touch one end to the hot terminal on the solenoid and the other to the S terminal ( the yellow and red wire should be on this terminal ).

The starter should work when you do this. This by-passes all other circuits.


Tony"

" I'll give that a try ove

" I'll give that a try over the weekend when I'm at the boat. Chances are that since the solenoid has been replaced (the old one was probably fine itself), this test will operate the starter. If this is so, and the other circuits are bypassed, does it then mean that the problem can only be in the circuit that exists between the harness plug and control box (ignition switch)?

If this were so, I should be able to close the ciruit(s) in the female part of the harness plug to simulate the ignition switch in START. Either the Seloc manual or my interpretation of it has been less than accurate about how to do this.

Any further advice is of course appreciated.

Thanks again,
Joe "

I have merc 65 hp with thunde

I have merc 65 hp with thunderbolt ignition that is not firing do you have any suggestions on how to fix this problem

" Joe,

The Seloc manual can

" Joe,

The Seloc manual can be ambiguous about some things. I looked through some wiring diagrahms for engines with the type of harness plug that you have, and found that they were not all wired the same.

You should be to jump these wires at the female plug. You would have to jump a hot (12 volt) socket to the socket that is connected to the yellow-red wire that goes to the solenoid. I would suggest that you try jumping the solenoid first. Then you can try at the plug if the first test works. If the battery cables are wired through the plug, there will not be any power when you disconnect the plug, but I think the battery cables are wired separately on you engine.

Tony "

Before I get too involved I&#

Before I get too involved I'd check EVERY wiring connection for rust/corrosion. It happens to me every time I buy an old boat out of someones back yard. Clean the wiring up and it cranks nearly every time.

" Thanks very much to all thos

" Thanks very much to all those that replied. The problem was finally found, and it starts and runs like a top again. I tried jumping the solenoid as suggested, and not surprisingly the starter cranked fine. This left only the control box and ignition switch as suspect- well, not quite.... I should have been able to close the circuit in the harness plug to simulate START from the control box, but couldn't. The pin that represented + from the battery did not have continuity in its pin position.

This left only the red wire itself (from solenoid to harness plug) suspect, but what are the odds that a clean wire with a solid connection and no corrosion just goes bad? I'd checked the inline fuse a gazillion times in this wire, but it appeared fine... appeared fine. In my (very) limited experience, I'd never seen a fuse break at one end, so that the tiny blown part was concealed past the viewable part- but I guarantee you it won't fool me again ;-) If I'd been a little more experienced, I would have known to try this test a lot earlier, but the knowledge I've acquired in this process is valued.

Joe "