Marine: Boating, Sailing, PWC, GPS and Navigation - engine won't turn off

just recently started repairing 1982 mercruiser 470;new battery;new slave solenoid,new ignition key switch, and had starter rebuilt, starts like a champ but wont turn off at key ingnition switch, any suggestions?

I'd go back and check the ignition switch wiring.

I have a 1971, 40 hp evinrude on which I have replaced the key switch, as well as points, condensers, coils, plugs - the works! Motor will not turn off -- wiring has been check, rechecked, and checked again and compared with wiring diagram. Swiitch has continuity on M terminals with key off but no continuity with key on, which is what it is supposed to do - yet the engine will not turn off. Apparently it is not grounding properly -- could the cut out switch be the problem?? However, I have pulled the black wires from this switch and have grounded them directly and still the engine runs off?? Help!!

iam going to take a guess since iv seen it before if you went over all wireing and cant find anything wrong you might have got a bad ignition key switch it happens

I had thought it might be the key switch and bought and put on a a second new switch and it did the same thing. Neither turned the engine off. Strangely, I put the old switch back on which had worked fine before it was replaced (i.e., was turning the engine off ok but was being replaced because it was causing the stater bendix to keep trying to engage), but when I put the old switch back on, it now did not turn the engine off! Really weird!

lI had stated I had checked the wiring -- i did not tear into the wiring harness wrap to check inside for a possible break -- I just hated to cut the wrap off the wiring, but may have to do this??

Thanks lenny -- you caused me to rethink the wiring possibilities. I inspected the wiring but could not see any defects! But could not get continuity thru one of the black magneto wires. I started peeling back a little of the sheathing coveriing the five wires and started probing the black wire which I could not get a reading on! I finally narrowed the problem down to a spot where I peeled back the wire covering and found a break. Apparently when I repaced the key switch I jiggled the wire enough to agitate the weak spot causing it to separate inside the wire covering! Now have continity thru this wire -- will replace wiring harness tomorrow and should have everything back to normal. Thanks again!

Would recommend this to kayot82 also!