Mercruiser dies after getting on temp

[nola mike]

You should only have 3 wires in most cases to the coil. Choke, resistance and starting. Disconnect all but the resistance wire. However it should still run fine with 12v until you fry your points. Also make sure that you have an external resistor coil.

 

[Scott Danforth]

points when cranking get their voltage from the starter "R" terminal (also called "I" terminal). however for normal Key-on, they get power thru a resistor wire, or a ballast resistor to drop voltage to approximately 9 volts.

you can run them "hotwired" to 12 volts for a short period of time, however they will burn out the contacts rather quickly.

 

[YOBE]

What Ballast resitor would you suggest? 1.2ohm or 1.5ohm?
A resitor wire is missing

 

[alldodge]

What Ballast resitor would you suggest? 1.2ohm or 1.5ohm?
A resitor wire is missing

How many wires are on the coil and what colors?

 

[YOBE]

How many wires are on the coil and what colors?

On the positive side of the coil are 2 brown wires. One was connected directly to the key-switch with some type of fuse in between that also gave a voltage drop. Fuse is removed.
Other brown wire is not going anywhere. I see a purple wire that has been cut lose and I guess this one is the resitor wire that was on the second brown wire.
And I added a new wire directly from the R on the starter to the positive coil

 

[kd4pbs]

Assuming the points are good, with the points open, you will measure full battery voltage on the coil + wire due to there being no current dropping the voltage through the ballast resistor/wire.
With the points closed, you will see the battery voltage minus the voltage drop across the ballast device.
With the engine running, due to the points opening and closing, you'll see some amount of voltage greater than what you'd see with them closed and the engine stopped. That amount will depend on the duty cycle of the points (dwell) and the condition of the condenser. More dwell will show a lower voltage here and less dwell will show a higher voltage because the higher the dwell angle (the smaller the points gap), the longer the points are closed.
Put your meter across the ballast device, set it to AC reading, and if you see a few volts while it's running, the ballast device is doing it's job.

 

[alldodge]

On the positive side of the coil are 2 brown wires. One was connected directly to the key-switch with some type of fuse in between that also gave a voltage drop. Fuse is removed.
Other brown wire is not going anywhere. I see a purple wire that has been cut lose and I guess this one is the resitor wire that was on the second brown wire.
And I added a new wire directly from the R on the starter to the positive coil

That could work

Note wire coming from helm was white

 

[Scott Danforth]

did you get your wiring straightened out?

did you get the points adjusted correctly and the dwell set correctly?
what did you set dwell and timing to?

 

[YOBE]

did you get your wiring straightened out?

did you get the points adjusted correctly and the dwell set correctly?
what did you set dwell and timing to?

Hi,
yes the wiring is sorted out. I added the necessary ballast resistor and this gives about 9V to the coil while running.

So this part seems to be solved.
Now focus will go to the points.

 

[Scott06]

So this part seems to be solved.
Now focus will go to the points.

Do the points first this is everything for a points type ignition. Recently took and old (1973) evinrude 9.5 out of the basement been about 8 years since last ran. Would barely idle hard to start etc . Point gap should be .020” was .015” on one .010” on the other filed and gapped them starts first pull now doesn’t stall out idling ….

 

[YOBE]

Do the points first this is everything for a points type ignition. Recently took and old (1973) evinrude 9.5 out of the basement been about 8 years since last ran. Would barely idle hard to start etc . Point gap should be .020” was .015” on one .010” on the other filed and gapped them starts first pull now doesn’t stall out idling ….

Hi, I understand now what dwell really is.
I don’t have a dwell meter. But could I start with using the feeler gauge to set the gap? And then set the timing (timing device is on order)

 

[Scott06]

Hi, I understand now what dwell really is.
I don’t have a dwell meter. But could I start with using the feeler gauge to set the gap? And then set the timing (timing device is on order)

yes gap roughs it in. then set timing. really need a dwell meter maybe know an older guy who is shade tree mechanic or hot rod tinkerer.

Very few folks know how to set points anymore. I use my dads old dwell meter from the 1960s as the one I bought in 1990 or so died.

this is a great video of how points ignition works and how you can get good results if points are properly maintained. At 4.45 or so you can see what a good spark looks like

this shows the gap setting

 

[Scott Danforth]

I own 2 or 3 Dwell meters (2 work). one is the one I inheirited from Dad , one is the Admirals late father's, one was mine if I can get it functional again

local FLAPS used to have dwell meters you could use, however that went away about 20 years ago.

 

[YOBE]

I own 2 or 3 Dwell meters (2 work). one is the one I inheirited from Dad , one is the Admirals late father's, one was mine if I can get it functional again

local FLAPS used to have dwell meters you could use, however that went away about 20 years ago.

Found one online to buy. About 40$. Will see…