Battery or Alternator?

[spider2081]

DieselSpider, Thanks I understand what you are doing. I found one cause of intermittents with the original starter is one of the field winding wires is soldered into the big copper braid the connects to the solenoid. I have seen the wire break at the soldered area of the braid where it fastened to the solenoid. Re soldered it and after that it worked ok.
Another possible cause of intermittent starter operation is the single bullet connector labeled C6 and C7 on later model Spiders on earlier models they was a small connector containing both wires. In both cases the connections are made on driver side fender well behind the alternator. C7 is in the brown wire bringing power to the ignition switch "start" section terminal 30. C6 is the red wire from terminal 50 to the starter solenoid spade terminal.

[DieselSpider]

DieselSpider, Thanks I understand what you are doing. I found one cause of intermittents with the original starter is one of the field winding wires is soldered into the big copper braid the connects to the solenoid. I have seen the wire break at the soldered area of the braid where it fastened to the solenoid. Re soldered it and after that it worked ok.
Another possible cause of intermittent starter operation is the single bullet connector labeled C6 and C7 on later model Spiders on earlier models they was a small connector containing both wires. In both cases the connections are made on driver side fender well behind the alternator. C7 is in the brown wire bringing power to the ignition switch "start" section terminal 30. C6 is the red wire from terminal 50 to the starter solenoid spade terminal.

With the Franken Spider I have to deal with what was done 3 owners ago to shoehorn an Isuzu Turbo Diesel and charging system with matching MSG5-T transmission into the 78 Spider which is longer than the Fiat engine so that the cylinder head is almost touching the firewall and the cooling fan had to be relocated to in front of the radiator as the water pump shaft is about a half inch from the radiator.

There are a lot of electrical issues to say the least yet it has been remarkably reliable. The Hitachi reduction starter is on the passenger side and the SOC design puts the exhaust and alternator (with vacuum pump for the brakes)on the drivers side having the exhaust header traversing the car under the engine just in front of the transmission with the intake from the Turbo crossing over the front of the engine above the timing belt to the passenger side intake manifold. The mechanical direct injection pump is on the passenger side with no throttle body or intake butterfly of any kind.

Glow plugs are run by a Ford style relay mounted on the firewall above the starter. There is in reality quite a "Cats Cradle" of unused wires under the hood of which I am slowly identifying the uncapped positives and working through the hidden taped up twisted wire connection with no solder or crimping device on them.

The relatively new (a few months old) solenoid on the starter throws strong when you put the ignition switch to the start position so I know that part of the system at least is working consistently however the plunger on the starter solenoid doesn't always appear to make contact to power the starter motor. I have considered putting an idiot light temporarily on the braided wire going to the starter motor to verify that its the relay not making contact when this happens since I have not had it act up and not turn the starter when I am at home and put a meter on it. No or a very dull light with no start would indicate the starter solenoid failing to make contact while a bright light and no start could mean a bad wire or a commutator fault inside the starter however when I replaced the solenoid and bench tested the starter there was no indication of a fault inside the starter.

I am still recovering from a recent motorcycle accident (slid on sand at 40 mph and had the bike roll me as it went over me) so I have put much of this on hold until the I heal up a bit more however I may bite and just put in the second Ford relay to send power to the braided wire feeding the starter motor itself regardless of whats happening with contacts in the starter solenoid.

[spider2081]

DieselSpider, Wishing you a speedy recovery. I used home made test light as you mentioned to trouble shoot my intermittent starter. I moved it to different points in the circuit. My thought was I was more apt to see a light than notice meter reading because my intermittent start problem occurred so seldom.