1976 45hp no spark

[Scoboa]

I have a 1976 45hp that I bought and getting back into working order. It was claimed that it ran last year, but I'm having problems with spark. I pulled the flywheel and cleaned and regapped the points, tested condensers, and coils, but to no avil I still get no spark. Is there a kill or deadman switch I'm missing? Engine cranks fine, shifter is in neutral but both plugs in wires still get no spark when held against the head. I went through all wiring all seams to be hooked up correctly. I'm running out of ideas. Thanks in advance for any ideas you can offer. I know I am one missed step away from the wind in my hair.

 

[Frank Acampora]

Re: 1976 45hp no spark

There are two brown wires (possibly black) that look like lampcord. They come from under the flywheel and connect one to each set of points along with the condenser wires. These brown wires are the kill circuit. Each wire must be connected to a different terminal om the engine terminal strip, one to white and one to blue. At the ignition switch, white must connect to one "M" terminal and blue must connect to the other "M" terminal. The two "M" terminals are in continuity when the switch is off, shorting the two brown wires and points together, killing ignition.

To test, remove both brown wires from the engine terminal and insulate the ends. Now try to get spark. If you do get spark, then the problem is downstream, either in the wire cable or the ignition switch. If you still don't get spark, then the problem is under the flywheel, possibly a short, bad condensers (I know, you tested them), or bad magneto coils.

The engine MAY have a deadman switch also wired with these. The switch usually has a red tab on top and will need a small plastic clip inserted into it. When the clip is pulled out--as when a man goes overboard-- the deadman shorts the two brown wires together, killing ignition.

Magneto coils are dual wound with the low voltage coils and the high voltage coils having a common ground. Testing between ground and hot side of the points should yeild a low resistance. If you get infinite ohms, there is a open in the low voltage coil. testing between the spark plug terminal and the ground on the magneto plate should yeild a very high resistance. Again, an infinite reading means that there is a break in the fine wire coil. Lastly, you must be certain that the ground wire from the magneto plate to the engine block is in place and not broken. The magneto plate is partially insulated from ground by grease and without the ground wire to the block you may not have sufficient grounding to get spark.

 

[Scoboa]

Re: 1976 45hp no spark

My engine does not have a magneto, it has an altenator. The white wire does go to the terminal block where it is tied in with another white wire and then to the negative on one of the coils, and the wire also runs from the terminal block to ignition. The other brown wire from the second set of points runs directly to the other negative side of the other coil. A blue wire from each coil the leads back to the terminal block and then on to the ignition switch as well. You are much more knowledgable than I am but the way everything is wired matches my Seloc owners manual. I'm replacing the condensers today to see if that might be it. Thanks again for you input.

 

[Nordin]

Re: 1976 45hp no spark

Scoboa your engine has a battery ign.system. It needs 12V from a battery to work just like oldschool car ign.systems. Check if you have 12V between bluewires at coil and ground. When the points are closed current flows through the coil. When points open the current still wants to flow but it will induce a spark in the plug at hightension side.
The batterysystem has a circuitbreaker check if it has poped.
The bluewires are feed with 12V from the ign.switch. Redwire at switch is "hot" from battery.
Check the ign.coils from cracks. It is very common on these systems that the coils will damage (burning primeside) from leaving the ign.switch in on position when engine is off.

 

[Frank Acampora]

Re: 1976 45hp no spark

Sorry! The way you worded removing the flywheel and testing the coils made me think it was magneto. At the switch, blue wire must be connected to the "I" terminal. If, with the points closed or open, you do not get 12 volts to the coil, then check the switch. (like Nordin said, Closing the points allows voltage to flow through the coil). Points should be set at .020 open. With the switch in either on or crank position, the "I" terminal should get 12 volts (nominal--could be as low as 9 at cranking)

If someone has installed a deadman it will be in line with the blue wire and will OPEN, stopping current, if it is activated or does not have the clip installed

 

[Scoboa]

Re: 1976 45hp no spark

That may be something there my manual has the blue wire on M if it should be on I that would keep the power from getting to the coil. I'll stick my tester on I and check for voltage.

 

[Scoboa]

Re: 1976 45hp no spark

That may be something there my manual has the blue wire on M if it should be on I that would keep the power from getting to the coil. I'll stick my tester on I and check for voltage. I also pulled out my magnifying glass and in the schematic it does indeed show the blue wire going to I and on of the M's is open. If the boat gods are smiling on me she'll be running tomorrow!