i got a 1983 305 mercruiser motor it turns over but it wont spark replaced the coil cap rotor and butten i have 12 volts to the coil the ponits look good
Take the cap off the distributor and have someone crank the engine. You should see a strong spark across the points. I've seen new points overheat and the spring loose tension, so they where not opening. (Mallory Dist.) and Coils with and without built in ballast resisters. So you need to make sure that you have the correct parts. Oil on the face of the points can keep them from firing.
Checking spark is sometimes done incorrectly. You need a Spark Checker. Holding a spark plug wire to the block is not the way to go. If the points and dwell are not correct, the timing can be off , so the engine will not start. Sometimes you think you don't have spark.
If the engine has been sitting, I'd check compression, and take a look at the carburetor.
Good advise from Richard C but one other thing to check is the shift interrupt switch,located where the upper and lower shift cables are connected on the engine or transom plate.It's a micro switch that kills the ignition for a split second when shifting.You can test them with an ohm meter,but I usually just unhook them for testing purposes just to be sure.Leave it unhooked while testing,but be sure to hook it back up as you will find it all but impossible to shift from forward to neutral if it's not working properly.
You say the points look good but have you actually checked them. They may not be separating like they need to. You need a feeler gauge to set the points. I'm not sure but I bet you're dealing with a small block Chevy truth be told. Call your local parts house and ask what the gap should be and set them where they say and see if that helps.
Comments
Take the cap off the distributor and have someone crank the engine. You should see a strong spark across the points. I've seen new points overheat and the spring loose tension, so they where not opening. (Mallory Dist.) and Coils with and without built in ballast resisters. So you need to make sure that you have the correct parts. Oil on the face of the points can keep them from firing.
Checking spark is sometimes done incorrectly. You need a Spark Checker. Holding a spark plug wire to the block is not the way to go. If the points and dwell are not correct, the timing can be off , so the engine will not start. Sometimes you think you don't have spark.
If the engine has been sitting, I'd check compression, and take a look at the carburetor.
Good advise from Richard C but one other thing to check is the shift interrupt switch,located where the upper and lower shift cables are connected on the engine or transom plate.It's a micro switch that kills the ignition for a split second when shifting.You can test them with an ohm meter,but I usually just unhook them for testing purposes just to be sure.Leave it unhooked while testing,but be sure to hook it back up as you will find it all but impossible to shift from forward to neutral if it's not working properly.
You say the points look good but have you actually checked them. They may not be separating like they need to. You need a feeler gauge to set the points. I'm not sure but I bet you're dealing with a small block Chevy truth be told. Call your local parts house and ask what the gap should be and set them where they say and see if that helps.