no spark, tried lots please help

[crazyoctopus]

alrighty, so i recently bought a 73 240z project car and i am stuck. the problem started with no fuel, but the fuel pump was bad, so i swapped in a new one and other than the lines being clogged, that issue is resolved. then i checked to see if i was getting spark, and i was not. so i replaced the distributor cap, points, rotor (the guy that spins in the distributor), coil, spark plugs, and plug wires (installed correctly checked twice). still no spark.

so i started to forum search to try to diagnose the problem.

==to check if i got spark or not i removed the plug wire from the #1 spark plug and put it close to the block, head, and spark lug to see if it arced.

-I checked to see if the coil was getting power by removing the ground wire, attaching a new one, and seeing if there was spark whever i touched it to brae metal.

-hard lined positive end of the coil to the positive terminal on the battery, hard lined a new ground to the negative side of the terminal, checked to see if i got spark, nope.

there are a few things attached to the coil and distributor that i am not really sure if i need them/ what they attach to, and they might be what is causing the no spark.

here is the coil

1. is a coil condenser? i think. this came with the car and the wire was borken so i spliced it back together

2. BY wire, is a wire that goes to, i think, the ignition.

3. is possibly a ground but i have no idea where it grounds out

4. i have no idea what relay it is

5. i have no idea what this is

here is the distributor

here is a condenser that i replaced, and there is a prong sitting at teh top of it that apparently goes to the coil negative side, but where would i connect it.

[EScanlon]

Zach:

You mention a 73, yet your profile says 72... so addressing it as a 73:

Check post #3 on this thread:

http://www.classiczcars.com/forums/showthread.php?t=29496&highlight=73+wiring

You'll find a schematic for the 73 Z as page 2 of that post.

If you then trace the wiring for the ignition switch, (which coincidentally is highlighted by the thread poster) you'll be able to see which wire colors go to where on the coil.

Without going into a lot of detail, your 4 and 5 connections are part of the ignition circuit once the car is running (12v+ running through the resistor to drop the voltage), and those are the connections to the resistor. By the way, it should be a Black/WHITE wire and not Black/Yellow. Could your wire just be a bit grimy/aged? There are actually TWO Black/White wires that go to the coil and resistor, as well as a Green/White. The resistor receives a B/W and a G/W, the other B/W goes to the + side of the coil.

As you have the coil wired, you've essentially "hot-wired" the car, except that you haven't provided a ground for the distributor, which connects to where you have the condenser connected to. It should be a Black wire coming from the coil's Negative post. (Wire #3)

Remove your jumpers and try to reconnect per the schematic and see if that will get you going.

HTH

Enrique

[crazyoctopus]

kk will do, and thanks for the link.

the car was made in 10/72, so that makes it a series 3, and closer to a 73; but every now and then the wiring seems closer to a 72, than a 73.

[EScanlon]

Easy way to distinguish it, if it has Intermittent Wipers, then it's more of a 73 than a 72.

Note that the YEAR isn't very specific, as US manufacturers changed production cycles in late summer (July/August) to coincide with Sept/Oct new model releases whereas Nissan was using a calendar year cycle (at that time) and in addition to that, many items were slowly changed through attrition of parts.

2¢

E

[crazyoctopus]

alright, so i checked the wire to the back of the tach, and that was fine, all of the wires were solid.

i took out my volt meter and found that i was getting 13V from the BW wire on the resistor to the GW wire on the reisistor. when i tested the power from the + side of hte coil to the - side of the coil it read 0V.

started looking at the connections, recleaned them, replaced the plugs and tried again. same results. since we were getting power to the resistor but not through the coil i figured that it might be a bad ground (B wire on - side of coil). so i added a ground wire to it, and FINALLY got voltage running through the coil.

while key is in the "ON" position and resistor connected i was getting...

+/- on coil is 6V

+/- on resistor is 6V

High tension (nipple from coil to distributor) to (-) on coil is 6v

while cranking the car

+/- on coil is 7.75V

+/- on resistor is 0V

High tension (nipple from coil to distributor) to (-) on coil is 8v

this is where it gets weird. when i connect the voltmeter to the the distributor cable it shows no volts running through it. when i take off a spark plug wire at any cylinder there is no spark running through it.

so i dunno, the coil now has power going through it. but whenever itwants to transfer to the distributor it shows no voltage, and i would think that there would be.

so what is the next plan of attack? is it in the distributor? i replaced the points, rotor, condensor, and cap.

[Neumeier]

You picture labeling suggests that the negative side of the coil is hard wired to ground. This does not seem correct to me. Generally, the positive side goes to the ignition (i.e. 12 V when the ignition switch is on) and the negative side connect to ground through the points. The way it works is as follows. When the points are closed there is a sudden surge of current through the primary circuit of the coil. This then induces a current in the secondary circuit of the coil (at a much much higher voltage) that provides sufficient voltage to get a spark. So, if your negative side is hard wired to ground, and not hard wired to your points, you will not get a spark. In fact, a steady current across the primary of the coil creates ABSOLUTELY NO SPARK.

[EScanlon]

Have you connected the (-) side of the coil to the Dizzy?

That voltage while cranking is off, should be 12v, 0 on the resistor (it's being bypassed) is correct.

What about the coil to dizzy cable and the other spark plug wires? New, or re-used?

FWIW

E

[crazyoctopus]

i actually have both now. i have a hard wire to ground, as well as a wire to the points.

the only way that i was able to get any power running through the coil was if i hard lined a ground on the negative side of the coil.

here is a photo of what the current set up is...

-escanlon i have a new coil, dist cap, points, rotor, spark plug wires, spark plugs, and dist. condensor. i am picking up a new coil resistor, and radio interference condenser tomorrow

Edited December 28, 2009 by crazyoctopus

[Walter Moore]

Disconnect the hard wire to ground.

The ground for the coil goes through the breaker points. When the points open the coil fires. (Counter-intuitive I know, but that is how it works.)

With your hard wire to ground from the negative side of the coil you have by-passed the points and the coil will never fire.

[crazyoctopus]

Alright I'll try it In the morning; but I can't remember the coil getting any power through it without the ground hardlined. I'll let you all know what happens when I get it back up to the cables

[Curtis240Z]

The spade terminal on the side of the distributor which is also connected to the the condenser on the side of the distributor should go to the (-) side of the coil. That should be the ONLY wire on the (-) side of the coil.

The (+) side of the coil should have two wires the condenser located near the coil and the wire from the ignition. Since you also brought another hot wire to this terminal, the coil will always to energized.

When this is wired correct and you still don't have spark, make sure your points are actually opening and closing.

[crazyoctopus]

ooOOOoo, so the black wire (#3 in first post) that is connected to the negative side of the coil currently is not supposed to be there. weird. from all of the posts that i have read there has always been a discussion about having that one attached (BW & GW to + of coil, and B to -).

where does that black wire go then?