Datsun Roadster Forum-311s.org

Hello! I am Patrick and I have a 67 1600. I was trying to get my roadster started this evening and the starter solenoid was sparking. This is a new starter. So I tested the wires that go on the positive post of the starter and the wires are testing 1 ohm resistance from the end of the wires to any ground and I know they should be reading nothing. This told me there may be a short but I just wanted to see if anyone may have any ideas, thanks!!

Patrick

Which wires arcing, the main lead to pos ,or the solenoid wire at spade terminal ? Solenoids do spark inside
1ohm isn't that bad for a cable length
The starter needs a good connection to neg on the engine mounting to access current , sounds like a open circuit ,not gaining a good connection to operate , a pos wire directly to neg side is an example of a short ,blows fuses etc. If the solenoid wire is grounding then its shorting , Measure voltage at the starter main lead and solenoid wire
Clean oxidation off connectors
Hard to access though

I got the engine to fire a bit, but when I did, this happened… not sure what is going on

Take your time Here! I'm not any expert on wiring, but have fried things before. I do know the main power wire coming from the alternator should be modified to have an inline 30amp fuse wired in to protect the amp guage. Main power also goes to the starter I think, and it takes only seconds to fry wires in places you may not even see. So, review some schematics, keep asking questions and take your time. Check the tech wiki for wiring... I know Curtis is one of our resident experts and has documented all the different wiring schematics from different years.

That's also sparking right underneath your gas filled carbs... fire extinguisher on hand please!

Thanks! Those sparks couldn’t be coming from a bad ignition switch right? The starter was sparking right when I was trying to start the car. But yesterday I spaced out the wires more at the connections and they went away. But when the car fired up for a second those sparks in the pics above came back

I don't think it's the switch. Make sure your battery cable isn't grounding against something... main power going there, strong enough to weld a ring on my hand to a 13mm wrench I had in there once (and ONLY once... learned my lesson!). Curtis makes a new starter harness... they fatigue from the exhaust heat. Again, please be careful... fuel and sparks...

Gregs672000 wrote: ↑Wed Mar 20, 2024 12:08 pm That's also sparking right underneath your gas filled carbs... fire extinguisher on hand please!

I was tightening one of the nuts on the bottom of my rear carb a week or so ago using my left hand and reaching in from the front….when I turned the wrench I made contact with the starter lead and it shot sparks and scared the crap out of me! Then it hit me that thank god it didn’t ignite some fuel on the carb I was working on!

https://www.amazon.com/dp/B0C4V5LWWL?ta ... psc=1&lang
I'm going to try / buy one of these type boroscopes using your cell phone
It's likely what's needed to see what's going on on your issue it might be foreign material in the armature, rust etc too .

So this is wild, I decided to test of the engine was holding voltage and maybe that was causing the spark so I hooked up the multimeter to the negative on the battery and now I can put the positive multimeter wire anywhere metal on the engine itself and it’s holding 12v. I have zero idea how this has happened lol.

praugust12 wrote: ↑Fri Mar 22, 2024 7:26 pm So this is wild, I decided to test of the engine was holding voltage and maybe that was causing the spark so I hooked up the multimeter to the negative on the battery and now I can put the positive multimeter wire anywhere metal on the engine itself and it’s holding 12v. I have zero idea how this has happened lol.

If it has a 10amp setting ,put it on neg post and the pos on neg cable if you've a IC anywhere radio etc.
See what mil amps, it's running 1 wire alt ? That draws 20 mil amp constant
Also auto relays have super capacitors ,,transistors that can show volts
The ign condenser stores power
And the multimeter drawing some amps could give a batt volts ...got a clock in it ?

Thanks for the replies! I actually figured it out. I decided to put an external ground wire from the starter to the frame itself and it dropped all the positive power going through the engine and I have no more spark!

Awesome! Yes, there area few grounds and they are very important!

In other words, now you have more current to the starter . Pos pulls current, not puts it out
Best to clean off the block to starter metal surfaces but its a beotch