1973 240z

[Jessie]

Help!!! ‘73. 240z won’t start. I only hear a click on relay but starter will not crank. It only crank if solenoid is jump start. Battery is @ 12 volts Replaced switch, clean all connection but all failed. Any suggestions is greatly appreciated. See video please 

829BEB0C-E8A2-4C39-A56E-53C15A7880CA.MOV

[RPMS]

Sounds like a bad starter motor.  I'd take it out, give it a couple of gentle whacks with a hammer and see if it spins when voltage is applied.  Rebuilt units are pretty cheap, last I checked.  Double-check me on this, but I think I once accidentally replaced my 240 starter with a 280 and it spun the engine with a lot more vigor than before, despite being cheaper.  

[ZHoob2004]

Sounds like the starter is gone. As above, try a few gentle taps on the starter (don't want to break the permanent magnets), or try replacing it. Direct drive starters are $30 on rockauto, or you can spend a bit more and get a gear reduction starter for a 280zx (no real reason to). If you do get a replacement, be sure to get the one that matches your transmission (auto/manual are different)

[Jessie]

Thanks for all your replies. I figured it out. I replaced the wire from ignition to solenoid and started right up. 

[jhm]

Good on ya'.  A lot of folks will measure their voltage at the battery, but that doesn't necessarily mean your starter and/or distributor is getting that full voltage.  The electrical systems on these old cars suck.  Never miss an opportunity to clean your connections and grounds, and replace the old wiring with new, thicker-gauge wire.