1973 Mercury 40hp won't spark

[wakruem]

I have a 1973 Mercury outboard 40 hp Model 400<br />w/ Thunderbolt Ignition. The motor has been<br />sitting in my shed for the past 3 years. I just started working on it to get it running again.<br />I have replaced the solonoid with a new one.<br />Also replaced wires from solonoid to starter and<br />from solonoid to battery. The motor cranks but will not fire. I have new spark plugs as well.<br />Anyone have any ideas.<br /><br />Thanks,<br /><br />Wayne

 

[steelespike]

Re: 1973 Mercury 40hp won't spark

Be sure to get a ser. manual before starting any repairs, Try the library,NAPA,amazon.com,iboats.com,ebay,etc.<br />Check for spark.If you have spark use WD40 as starting fluid.If it starts you have a fuel supply problem.

 

[Trent]

Re: 1973 Mercury 40hp won't spark

Check for spark at each plug wire to ground. If equipped; is the kill switch installed?<br /><br />Make sure the engine is cranking at "Full Cranking Speed" These engines must have full speed to have the correct spark at the sparkplugs.

 

[12Footer]

Re: 1973 Mercury 40hp won't spark

To carry what Trent said a little further, look for an orange or black with yellow stripe wire in the harness leaving the switchbox and going to the helm. Unhook this wire at the switchbox.<br />See if you now have spark. If the engine starts running at this point, you will be unable to shut it down,except by maybee choking it. But if it does run,you know you have a problem with the ignition switch,lanyard switch,mercury tilt switch, or wire harness,regarding this wire to ground.