1996 Mercruiser 3.0 Alpha One turns over and over, won't fire

[Lakelife75]

I need some help, I traced the problem to no coil voltage when I start. I get no voltage at purple wire going to coil when starting, so I jumped 12V directly to the purple wire and it fires right up, but cuts off if you disconnect it, first suspected slave solenoid, but then realized that shouldn't matter after it's started. I have 10/11V on yellow/red wire coming of starter solenoid when switch is turned on. I first thought it was the interrupter switch, but realize it only closes contact when putting into gear, and I think it goes to ground then. Can that switch be bad and staying grounded? I am getting continuity from purple on alternate to purple on switch, and just happened to put meter on 2 screws attaching switch to motor and get continuity there. Also jumped out safety switch at gear shift, that does not fix it.
Any other ideas.

 

[alldodge]

I need some help, I traced the problem to no coil voltage when I start. I get no voltage at purple wire going to coil when starting, so I jumped 12V directly to the purple wire and it fires right up, but cuts off if you disconnect it, first suspected slave solenoid, but then realized that shouldn't matter after it's started. I have 10/11V on yellow/red wire coming of starter solenoid when switch is turned on.

With voltage there and your not cranking the engine this is not correct. Voltage should be there only when the engine is craking.

I first thought it was the interrupter switch, but realize it only closes contact when putting into gear, and I think it goes to ground then. Can that switch be bad and staying grounded? I am getting continuity from purple on alternate to purple on switch, and just happened to put meter on 2 screws attaching switch to motor and get continuity there. Also jumped out safety switch at gear shift, that does not fix it.
Any other ideas.

With continuity between 12V ALT output and ground, there is another issue.

My first thought is you have either a bad key switch or a break in the wiring between the key and purple wire. Turn the Key to ON and then see if you have 12V on the purple wire at the key switch. If that is good, measure 12V at pin 5 on the engine cannon connector

 

[Bondo]

Ayuh,.... Welcome Aboard,..... Do ya have power at the coil's (+) terminal, with just the key, On,..??

When crankin' the motor on the starter, coil voltage is supplied from the outside tiny terminal on the starter's solenoid, through I believe a purple/ yellow wire,...

 

[Lakelife75]

AllDodge, I mispoke, the enginer was cranking when I got te 10V, remember having to stabilize ampmeter when cranking. I did have 12V on key switch purple wire, and jumped out the on/off safety switch, but I will have to check 12V at pin 5.
Bondo, I don't know 100%, but do not think I had any Voltage with the key on. I was getting 10V off the starter solenoid terminal, but it's yellow/red and goes to the slave solenoid.

 

[Lakelife75]

I also do know that the interrrupt switch is open when in neutral (which I thought was the problem, but I bypassed it by plugging the purple and whtie/grn wires together, and it still did not start.

 

[alldodge]

Instead of checking the cannon plug yet check at the Alternator and the coil with the ignition on, if its not there check the cannon plug

 

[Bondo]

Bondo, I don't know 100%, but do not think I had any Voltage with the key on. I was getting 10V off the starter solenoid terminal, but it's yellow/red and goes to the slave solenoid.

Ayuh,.... That's the inner tiny terminal,...

The outer tiny terminal goes to the coil to provide battery voltage to the coil,....

If ya don't have the outer tiny terminal, ya might have the wrong starter,...

 

[Bondo]

I also do know that the interrrupt switch is open when in neutral (which I thought was the problem, but I bypassed it by plugging the purple and whtie/grn wires together, and it still did not start.

Ayuh,.... An open switch is Right,....

Joinin' the wires kills the ignition,....

 

[Lakelife75]

I'll check the alternator to coil Continuity? or voltage? when I get back to the boat. Will cbecking at te cannon plug eliminate speedo, ign and safety switches?
Bondo, if that is right and the interrrupt switch is normally open (neutral), could it be grounded? Seems like a bad design to me to failling in that manner, but seems like what I found. Purple wire on alternator to purple wire in one side of the interrupt switch has continuity, and I also had it on the "terminals" on top of the switch, which are probably the mounting screws and that would make it grounded. Does this sound right?

 

[Lakelife75]

I had continuitty to coil, between purple wires. Also tried disconnecting grey wire from coil (local boat place recommendation) and also disconnected purple, that did not work. I did verify purple wire is grounded. Tried to get cannon plug apart, but connection looked perfect and couldn't get unplugged. Hooked everything back up one last try, dang thing starts!! Just Great, now I really don't know what it is. Could be ign. switch, messing wtih cannon plug, who knows. Thanks for all the input!

 

[alldodge]

I did verify purple wire is grounded.

The purple wire is power to everything, it is not to be grounded, you will blow the fuse.

You keep talking about continuity, this is good to check a wire, but you need to be looking for 12V on the purple wire