Re: Ground Problem?

[Don]

quote beerman57:

Already tightened the cables at the batteries. So starter condition makes no difference how much voltage is coming out of the solenoid, right? A very tired starter when cranked should still have 12V coming out of the solenoid (not 5V) when 12.8V is going in? I have the old (almost new) solenoid out in the garage, if it tests OK, then it “almost” has to be bad ground.

Well, not quite….A tired starter that is drawing way too much current will throw off test results and add to confusion….
But, you mentioned the owner saying the engine cranked normally when the two large solenoid terminals were "jumped", did I understand you correctly? If so, this would seem to rule out the starter as a problem. Did you try jumping the terminals (key switch off-gas wiped out of motor pan)? You also mentioned that the owner had replaced the solenoid, is this the case?
If indeed the owner replaced the solenoid, and the starter operates normally when you jump the big terminals, then I feel it is safe to conclude that the solenoid inputs are to blame: bad ground to solenoid or voltage loss through the orange/yellow input lead from key switch….
And again, the voltage drop tests in most OMC manuals will help pinpoint the exact cause, just be sure to follow the instructions step by step starting with load testing the battery….