Re: 1970 4hp weak spark
If the 4HP has electronic ign like this:
http://www.mercruiserparts.com/Show...&bdesc=FLYWHEEL,STATOR+AND+IGNITION+COIL+(40)
the stator is completely self-contained and does not have an external capacitor, charge coil, etc.
Since you do have some spark, here's a couple of things to do before condemning the stator:
1) Replace the white insulator block where the external wire connects to the points. This block will crack/degrade with heat/age and short the stator output to ground.
Insulator: Mercury 336-3981 (NLA but may be available Old Stock at your local dlr), or Rapair 994-3981.
http://www.boatfix.com/bykeywordnew2.asp?textfield=994-3981&texttype=2&submit=Search
2) Check the coil for cracks & arc burns. Very common to see on these old-timers. Sometimes they're bad enough that you'll hear the arcing when they're running. You'll have to remove the coil and peel back the rubber cushion in order to check all sides for cracks.
While it's certainly possible for a coil to be bad and show no cracks/arcs, it's not quite as common. You can check the coil for proper resistance values with a meter, as necessary.
If the above doesn't do the trick, most likely the stator is shot. If you can get hold of a later-model parts motor, you can upgrade to the more reliable-style ign with external charge coil & capacitor. eBay would be a likely source of parts.
HTH & let us know what you find...........ed
