Re: mercury 4.5 hp problems
Ron, many times this is caused by a sheared flywheel key. If the key shears, the flywheel is out-of-synch with the ign and can cause problems such as backfire or kicking back.
You'll need a harmonic balancer puller or other suitable gear puller and some grade-8 puller bolts to get the flywheel off.
You can look up parts here, just open the parts diagrams with your motor's serial number range:
http://www.mercruiserparts.com/SelectModelType3.asp?class_id=2
While you're in there, take a look at the points, if they look gnarly just clean them up to bare metal, degrease, and gap to .020". This type of ign system "makes" to fire and the points handle very high voltages, so they do tend to look a bit crispy.
When you're done, torque the 7/16" flywheel nut to approx 35 ft-lb. and you're done.
HTH.............ed
