TOPIC: 150 hp ignition

i picked up a 1977 150hp inline merc serial #4603127. i would like to fire it up but i don't have controls yet. does this ignition require 12 volts to the switchbox and if so which terminal. i have included two pictures(i hope).the top red wire goes to the coil,the third wire down from the top looks white,the bottom one is red.
thanks

Only one pic showed up and your text does not match the pic. It does need 12 V and it is connected to the red terminal which is the second from the bottom. The brown terminal is for a tach but some versions take the tach off the rectifier. Make sure you tighten that ground cable on the starter motor.

if you start it up without the harness you will burn out the rectifyer so disconnect the 2 yellow wires on the rectifyer.

yes my text was wrong,the white is on the bottom and the red is above that,thanks dave. i will disconnect the yellow wires on the rectifier,thanks dave.

Us Daves are here to help And yes, as Dave B said, disconnect they yellow wires and remove the recifier (if its there).

I think you need power on two of those terminals. One is constand power and one is switched power to turn the ignition on and off.
Conrad

From top to bottom

#1 is coil
#2 is ket on off need + for run
#3 is + also to run
#4 isnot neededto ruN
Then ground from coil


remove the yellow wires from the rectifyer. jump the starter and it should start if not check for spark first.to stop remove wire from #2

Took a little looking, but I thought I remembered Dr. Frankenmerc posting a pic and instructions on how to go about this;
www.fiberglassics.com/fiberglassics-forums/mercury-outpost/paging-dr-frankenmerc#10093
(Scroll down close to the bottom)
It's on a 1970 model 1150, but I think (?) it's still good info for your situation.

Be careful as Dave B has it wrong.

Top Green terminal (red wire that should be green technically) coil.

Next down is the Brown terminal for the tach sender wire on old Quicksilver tachs. (not used with 6 pulse tachs)
Next down is the Red Terminal for the red 12v+ constant voltage wire.
Next down is the White terminal for the white wire which is 12v + only during start & run.
Below is the black (-) ground wire from the coil unless the coil is grounded to the crankcase.
You will need to apply 12v+ to both the Red Terminal & the White Terminal with the battery's (-) also being attached to the engine ground (-).
Once the beast is started you will need to dis-connect the white terminal's 12v+ supply to kill the engine.
Great point on dis-connecting the stator yellows!
Thom

thanks for the replies,it looks like that ignition system is the same type as the one in a 1971 65hp i had a few years ago. i am hoping to see if she will fire this weekend. it is 19 degrees out at the moment so i am not in any hurry to go out.
steve d

Just be careful guys because there are a variety of different switchboxes and ignitions that might at a glance look the same so always compare your switchbox and wire color codes to the appropriate wiring diagrams before zapping them with 12v in the wrong place, etc.
There are several ignitions in Mercs that look like they need 12v applied 'somewhere' when in fact they make their own voltage by use of their stator (alternator) or solid state magneto that creates its own juice via the magnets under the flywheel and the magic of electricity.
Many a switchbox and other ignition components have been fried by the application of 12v.
signed,
The voice of experience
Thom
and,..you wouldn't believe the carnage that can occur from hooking the boat battery up bass-ackwards. (my neighbor & just after I had fixed everything for him - sigh) Amazing how far out the potting will swell in a switchbox before it completely dies internally.

i wired the switchbox according to the diagram poured some gas into the carbs and she fired right up. the #6 spark plug threads seemed a little soft, what's the best way to fix the threads,helicoil?

Helicoils will work, but make sure you are square with the helicoil tap or you plug will not seat flat and seal. I tap while running a vacuum cleaner to pull the shards out throught the flutes in the tap. I also have the offending cylinder hanging off my workbench, spark plug opening facing down so gravity is also helping tap shards from entering the cyl. Aluminum is soft, so in the unlikely event you do get some in the cyl, it'll blow out the exhaust ports quick on start up with out causing damage...sounds terrible I know but the motor will survie fine.
Randy

i also put grease on the tap to hold the chips and clean and regrease it 3-4 times before i finish the tap

I prefer the K&D inserts over the 'heli-coil' because they are a solid insert with a nice flat surface for the sparkplug to seal against.
#6 hole is a toughy to get properly aligned on so take the time to remove the lower 'U' shaped cowl, and drop the lower pan loose front fore and aft so you can sag the pan low enough to get good alignment.

access to the hole was going to be my next question, i was thinking i might have to pull the powerhead. this is my first 6 cylinder so i will have to build a stand that will support it and then i will get into it.
thanks again

A quick way to make a stand is to drill the hole pattern for the bolts into your workbench. Use the gasket that you are going to have to get anyway if you pull the powerhead...as a template for the holes. If you have a fancy schmancy workbench you can always put plastic plugs in the holes afterward. Once you catch mercury fever though you are more likely to put another block in the stand.