No Spark at all

[spider2081]

I think that diagram shows a light blue/black wire feeding 12v from the ignition switch. With that wire connected to the coil + terminal disconnect the brown wire on the coil and let us know what the + side of coil then reads with the ignition switch in the run position.

[LuisMateoSpider]

Yes

I removed the brown cable, and the L.Blue/Black reads 12v against ground. The same cable reads 12v against the brown when is not connected to the coil. Once both connected to the coil they measure 7.5v but I thhnk that has something to do with the internal component of the coil.

What else can it be?

[majicwrench]

"I checked the points and they seemed fine" not sure how you checked them, just looking at them is not gonna do it.

It can be lots of things. Here is how the system works, current runs to the coil (you have that) then it goes from + wire thru the coil and out the - terminal ( yours is doing that). Once current comes back out, it runs to the points ( or in this case the relay, then the points) Once at the points, the current flow is gonna get shut off and on as the points open and close (ground). This is what make the spark from the secondary part of coil.
So, on your car, the brown - wire is grounded all the time, that is why when it is hooked to the coil the voltage drops. It can be shorted/damaged somewhere tween the coil - and the points, or (most likely) there is a problem with the points. Do you know where the relay is?? Unplug it, see if voltage at coil comes up. It likely will. This mean the short to ground is further down the line. Plug relay back in. Unhook both sets of points. Now is voltage up at coil??
Report back.

[spider2081]

I think if you measure 7.5 volts on the + terminal of the coil and the Brown wire on the coil you have more than one issue. First I believe the + side of the coil should remain almost battery voltage whether the brown wire is connected or not. The fact that terminal drops from 12 volts to 7.5 volts means there is a bad connection between the battery and the coil + terminal.
I believe the brown wire terminal should be 12 volts with the brown wire removed and Zero volts with the brown wire connected and the points closed.
Does your distributor still have 2 sets of points??? some have been modified to have just one set.

[LuisMateoSpider]

Ok,

I removed the relay and with both (+ -) disconnected it gradually goes to 0v, when I use regular ground it reads 12v, then I read the L.Blue/Black with the Brown and it gradually goes back to 0v, all this without the relay. Once I connected the relay back it goes to 8v, with or whiouth being connected to the coil.

How can we test if the points are the problem? Or should I just replace them?


Here is a pick of where my relay is:

[LuisMateoSpider]

Yes spider 2081

The + side of the coil reads 12v. And yes I have a 2 points distributor, I world be interesting on an digital but not anytime soon.

[spider2081]

I am not very familiar with the dual point cars. The couple I have seen have the relays mounted on the passenger side fender well in the engine compartment.
The relay in your photo with a white/black wire disconnected has 2 terminals on it. The relay in your schematic has 5 terminals on it so I don't think they are the same relay.

[seabeelt]

Since you have the wiring diagram, start at the beginning of the power source and start tracing the power and ground routes to identify a problem/short/frayed wire/broken wire, etc. trace each wire in the circuit. This will lead you to the problem. Since you have dual points, if you follow the tune up proceedure, you can jumper one set of points out of the system at a time to eliminate one set and then trace the rest of the wiring. Dual points can take a while to get BTDC timing and dwell and point gap set correctly for both sets, but it can be done. Keep us posted

[majicwrench]

Again, you really need to provide accurate info.

"I removed the relay and with both (+ -) disconnected IT gradually goes to 0 volts"

"Once I connected the relay back IT goes to 8v"

What is "IT"?? which wire?? I'm not trying to be a pain, and would really like to help, just can't make out what you are saying.

According to the diagram, the Lblue/whited (OOPS EDIT this should be Lblue/black!) wire should read 12 volts unhooked from coil with or without the relay plugged in. Does it??

[spider2081]

I'm Confused where is the lt blue/white wire you guys are talking about. I don't see one in the posted diagram.

[seabeelt]

On the 78, The lt blue/white goes from fuse 1 to the fast idle circuit. It looks like you are testing the wrong wires, or your car's wiring is different than the diagram. You should have 12v on either side of fuse 1 with the key on. fuse 1 with a lt blue/black wire should go to the B+ side of the coil there are no interuptions in between, so you should have 12v on the B+ side of the coil. If you do not then you have a problem with the lt blue/black wire. If yes then, The brown - brown/white wire from the D- side of the coil should run to the ignition mode relay 128/2 pin 30 ( this is the relay where you can jumper out one set of points Remove the relay and jumper pin 30 to either pin 87 or pin 87a (jumping brown wire to either green, or green/black stripe) this will remove the fast idle circuits. (THIS looks to be the red socket in you photo that is missing the relay) test the voltage again. do youstill have 12v at the coil? If yes, car should start (caveat, points are set correctly and timing is set correctly. If it doesnt start, swap the jumper wire from 87 to 87a or vice versa maintaining the connection to pin 30. try again start the car.

basic question.... are you sure the points are gapped correctly and that the distributor is correctly set for 0 deg BTDC for the running points and 10 deg BTDC for the starting points ( I may have that backwards... going on memory here but you get the point)


second basic question... have you measured the impedence/resistance of the coil.. if not do a search on the forum to get the correct numbers, but i think they are in the ball park of primary 10,000 ohms and secondary 2-300 ohms. needs to be checked with all of the wires removed.

r/
If the car starts, then you have isolated the problem to the fast idle circuit (lt blue/white wire)

[majicwrench]

Spider 2081 caught my error, and I edited it in my previous post, the wire in question is Lblue/black!

[seabeelt]

Thats what i get for not reading the whole thread

[spider2081]

So I think there is an agreement there should be battery voltage on the + terminal of the coil when the ignition switch is in the run or start position. This is measured between the terminal with the Lt blue/black wire connected to the coil and ground.
With the other terminal of coil (brown wire) disconnected the D terminal should read battery voltage also. With the brown wire connected to the D terminal of the coil the D terminal should either read battery voltage when the points are open or 0 volts when the points are closed.

Can someone confirm the physical location of the ignition mode relay on this car.

[76was124]

I have a suggestion which takes a different approach, but I would suggest you wait for comments from the more knowledgable members already providing suggestions before you attempt this.

My thought is that If you read 12 volts without the coil connected and it drops to 8 volts when the coil is connected, that can result from only one of three things.

1. Abnormal resistance in the + wire from the corresponding connections back to the battery + terminal
2. Abnormal resistance in the - (brown wire) from the corresponding connections to the battery -(neg) terminal.
3. A short in the coil of sufficiently low impedance to cause the normal resistance of the wire and connections to drop 4 volts across it.

I feel pretty comfortable in saying it's NOT #3 unless wires are melting.

So if it was me, leaving all the coil wires connected as normal, I would do the following:

Read this entire thread before doing any of the steps!!!

Get a long wire and connect one end of the wire to the battery + terminal and the the other end to the coil + terminal. One of two things will happen:
A. If with the voltage you've been measuring to be 8 volts is now 12volts, you know the problem is in the + part of the circuit and you should move the long test wire off the coil to one connection point in the circuit closer to the battery until you find the bad connection. The bad connection will be between the last place you read 12 Volts and where you see the 8volt reading show up again.
B. If you do that initial test with the test wire on the coil+ terminal and the voltage across the coil stays 8 volts the problem is in the - (neg) part of the circuit. So next, remove the test wire from the coil and battery and connect one end to the battery - (neg) terminal and the other end to the coil - terminal. If the voltage is 12 volts, move the test wire off the coil to one connection point towards the battery until you find the problem connection.

WARNING!! For safety reasons I would put a 10 or 20 amp fuse in line with the test wire, just in case you end up with a dead short by accident.