Datsun Roadster Forum-311s.org

I’m still working on my 69 2000 redo. Now I have a new problem: it’s always started VERY easily until I took off the tach cable to replace it (new one on the way). Now it won’t start all! I think it must be a coincidence as I can’t think of any reason to connect taking this cable off and not starting. On the other hand, I’m a complete noob as far as the engine goes. I’ve checked the distributor cables and all are still attached. The engine turns over rapidly but won’t “catch” at all. Am I right about this just being a coincidence and not related at all or does taking the cable off the distributor mess things up?

The only thing I can think of is that the cable was providing a ground for something electrical

Ya, IF things were right before then removing the cable would make no difference. Does sound spark related, so pull a plug wire or the coil wire and check for spark (stick an insulated screw driver in it, have someone crank the motor and see if it will spark to metal while cranking... don't shock yourself). I suddenly recall a time when I forgot to reinstall the rotor once...

If no spark well have to figure out why...

I agree with Greg, sounds like you have dislodged or broken a wire somewhere. There are a lot of different wires along the tach cable path. Possibly the resistor for the distributor. Check for spark working backwards. Spark plugs then points- distributor at cap. Are you getting voltage at the coil? Continuity at the resistor? Gotta be something simple.

I found a loose connection at the coil and fixed that. Now when I turn it over it backfires (new!) but won’t start. The backfires are irregular and at most about one every 10 seconds or so. Again, prior to my messing around under the hood, the car started really easily, almost the second it started turning over. Being a noobie, anything under the hood is a bit of a mystery! Any ideas?

The distributor looks new, I lightly sanded the rotor, the cables look good. I’m going to try a spark tester in each of the plug wires. Timing? Coil? I’m a little over my head!

Some spark on 3 and 4 but erratic or none on 1 and 2. Sounds like I should go with new points, condenser and rotor, +/- wires?

Dster wrote: ↑Wed Apr 24, 2024 6:24 pm Some spark on 3 and 4 but erratic or none on 1 and 2. Sounds like I should go with new points, condenser and rotor, +/- wires?

Wouldn't hurt... wear/tune up items for sure. The condenser can go bad and pull spark from the points. Check point gap, check for corrosion on the cap and rotor. Check plug wires on known good connections (3 or 4) or consider replacements.

You'll get it, we're here to help!

Maybe the distributor accidentally rotated when you were removing the tach cable? Timing is now off?

Thanks to both. To Jeff: the bold holding the distributor from turning has been very tight so it’s almost impossible to turn the distributor. You could put what I know about timing into a thimble, but I did loosen this bolt and turn the distributor a very small amount to no effect. I’ve heard that to really set the timing correctly, the motor has to be running.

If you're consistently getting spark to some wires and not to others, it suggests that the points, coil etc are all working, but not sure if correctly adjusted however. The points are an on/off switch that has to remain open for a period of time (called dwell) and is set either using a feeler guage to set the gap when the points are being opened by the distributor's cam, or set using a dwell meter while the engine is cranking. I can imagine it's possible that there's just enough variation to open wide enough to spark some wires but not others, though that may be a stretch. The next connection is the rotor to each plugwire cap post and if they are damaged or corroded then it won't transfer (high tension/coil) spark to the plug wire and thusly no spark at the plug. You'll have to trace things back to determine where the failure occurs.

Points wear and show pitting over time, degrading/changing the gap. The condensers do something regarding spark, but I do know they can go bad and pull spark from the points, often creating intermittent ignition though I don't think it's usually just certain plug wires. Rotors and caps wear from transferring high tension power through them. Your coil is constantly charging, releasing and recharging to fire the plugs and usually won't fail on only certain wires or consistently fire only certain wires.