No spark - shotty wiring

[Stuckinthegarage]

Hello all, 

New to the forum and z cars! I have a '73 240z original engine and just did a major tune up - oil change, spark plugs, PCV valve, distributor cap, rotor, points, and condenser. I went to start the car and I wasn't getting much. I checked the battery and surprisingly it held a charge of the Buffalo winter but the CCA's were low so I decided to replace the battery since it was 4 years old. Now the car turns over but I am not getting a spark at any of the spark plugs. I pulled the distributor to check the gap and rotating to the highest point I'm gapped at .020 or .508mm which is well within spec. I checked resistance of each spark plug wire and most read about the same but will be replacing them tomorrow when I get a chance. 

 

On to the wiring and more about the car. So the previous owner removed the smog pump. And a lot of the wiring inside the engine bay was spliced and/or painted over. When I was replacing the distributor after checking the gaps I noticed there is a wire that isn't connected to anything and there isn't anything connected to the throttle control valve. I cant remember anything being there, not sure if its necessary (sorry if that's a dumb statement) and not sure if its causing the NO spark. Since there is no easy way to identify that wire, I'm at a loss. Please let me know if you have any suggestions.

[Zed Head]

With the key on you can actually see a small spark at the points by opening and closing them.  That's a good starting point.  People often jump straight to spark plugs or coil wires but the first spark is actually at the points.  If you get spark at the points then that means the coil should be producing a voltage. Tthen you can go to the main coil wire, then the cap and spark plug wire terminals.  That's my method, follow the path...

If you have a meter you can measure voltage at several spots to see where it's not making it through.

[Stuckinthegarage]

11 hours ago, Zed Head said:

With the key on you can actually see a small spark at the points by opening and closing them.  That's a good starting point.  People often jump straight to spark plugs or coil wires but the first spark is actually at the points.  If you get spark at the points then that means the coil should be producing a voltage. Tthen you can go to the main coil wire, then the cap and spark plug wire terminals.  That's my method, follow the path...

If you have a meter you can measure voltage at several spots to see where it's not making it through.

Thank you for your input. Last night I checked the following

- Ensured Firing order on cap was correct

 -Checked all distributor wires were tight with continuity where between wires

- battery voltage to coil and distributor with key on

-1.6 ohms between primary coil

-And 8.7k ohm on secondary

Can you walk me through checking for spark at the points? Is this done with the distributor out of the block? Please advise, thanks

[Stuckinthegarage]

11 hours ago, Zed Head said:

With the key on you can actually see a small spark at the points by opening and closing them.  That's a good starting point.  People often jump straight to spark plugs or coil wires but the first spark is actually at the points.  If you get spark at the points then that means the coil should be producing a voltage. Tthen you can go to the main coil wire, then the cap and spark plug wire terminals.  That's my method, follow the path...

If you have a meter you can measure voltage at several spots to see where it's not making it through.

Thank you for your input. Last night I checked the following

- Ensured Firing order on cap was correct

 -Checked all distributor wires were tight with continuity where between wires

- battery voltage to coil and distributor with key on

-1.6 ohms between primary coil

-And 8.7k ohm on secondary

Can you walk me through checking for spark at the points? Is this done with the distributor out of the block? Please advise, thanks

[Zed Head]

Just turn the key on, and turn the engine and/or the breaker plate to a position where you can close and open the points by twisting the distributor shaft.  As the points open or close you'll see a small spark across the point gap.  You can also measure voltage at the points to be sure your connections are good.  With the points open you should see battery voltage on one side and continuity to ground on the other side.

It's just another way to get in to the basics of how the system works.

[Mark Maras]

 Back to the beginning. Is this the first time you're firing an old engine or if it was running before the tune-up, where there any problems then?

[Stuckinthegarage]

Thanks zed head. I will try that today

 

[Stuckinthegarage]

Mark , the car was running last fall. Not any problems like this back then. I did notice today the ground wire coming off the negative battery terminal going to the firewall is badly rusted through. I will be relocating the ground to see if that helps. That may be the part of the issue too?

[Mark Maras]

 Relocating the battery ground wire to a secure connection is a good idea but If the engine would turn over, the ground was good enough to complete the starter motor circuit. I'm going to assume that it should have started before the tune-up. That leads me to believe it is either parts related or an installation problem. I'm going to out on a limb here and ask you to replace your new condenser with your old one and try to start it.

[Zed Head]

Might as well measure continuity to ground on the ground side of the points also.  If the distributor has lost its ground then the points won't work.  I'm just a big fan of measurements.

[Stuckinthegarage]

2 hours ago, Mark Maras said:

 Relocating the battery ground wire to a secure connection is a good idea but If the engine would turn over, the ground was good enough to complete the starter motor circuit. I'm going to assume that it should have started before the tune-up. That leads me to believe it is either parts related or an installation problem. I'm going to out on a limb here and ask you to replace your new condenser with your old one and try to start it.

Yeah, I figured it was good enough since the starter engages. I probably should have started it up before I did the tune just to get a base line (know that it was actually going to start up before I did the work) i was just about to start putting in the old distributor parts to see if I could get it fire last night but it was too late. Im going to try a few things tonight and if that doesn't give me any answers I will swap the old parts back in. Thanks everyone.

[Stuckinthegarage]

Ok. So checked several things and I won't bore you guys with too many details.. But I ended up putting the ignition to the on position and cranked the engine by hand to observe a spark. I got nothing so I ended up running a screw driver between the point contacts and I would get a faint spark. I swapped the old points set back in and I get a nice spark. I purchased the point from Zcar parts in the major tune up bundle, but seems as though the points themselves are slightly askew when sitting in my hand. Also, cracked the rotor when messing around with it.. So it looks like im back to square one. I'll be waiting on parts but will let you guys know if I have any more problems.