No spark...have diagrams....need wiring experts inside

[Jim_0068]

Ok......so here is the situation:

Car is back together and i have power, fuel, air and no spark so i'm like thiiiiiiiiiiiiiiiiiiiiiiiiiis close to getting it running lol.

Right now my problem is that the CDS/CDI unit is buzzing so i know that it is working and getting power. So i wanted to trace the 3 wires coming from it and make sure they were hooked up correctly and this is what i found:

Wire "A" should go from the CDI connector to the Ignition transformer (aka coil). This is a blue/yellow wire in the diagram and is in my car. This wire is fine.

Wire "B" is a red wire and according to the diagram should go to an electrical connector (aka splice) and then to the other 14 pin connector. Again i have this wire, this color and it goes where it should.

Wire "C" is a black wire and should be going from the CDI unit to the distributor and connect on the side of it. According to the wiring diagram this should also be connected to a blk/purple wire.


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Wire "C" is where i have problem. According to the diagram these wires should be on the distributor right? Well neither of these are. They are "jumped" together for some reason. I didn't do it, did the previous owner do it or should it be this way and i'm reading the diagram wrong?

The other end of the blk/purple wire goes BACK to the 14pin chassis connector (the main one) and i have it in the #9 position as it shows in the wiring diagram.




So is the above correct or is there some fishy wiring going on? I'm sorry if this is a little confusing but wiring always is. I'm going to take some pictures of what i'm talking about in the next day or two and post them up so that way maybe some of you can get a better visual.


Thanks

jim

[Jim_0068]

hmm....i think i might know what is going on.

While searching through all of the threads tonight i just might have it:

Even though wire "c" from the CDS unit and tach wire (blk/purple) are jumped there is a large balck wire that i THOUGHT went to a ground but i'm guessing that it goes to the negative side of the coil.

Make sense? Maybe?

thanks

[Early_S_Man]

NOPE!!!

The Black wire and Black/Violet wire are SUPPOSED to be piggybacked at the distributor points terminal! Unless they are connected to thedistributor ... engine wont run!

You can test the entire CDI system by connecting a grounded spark plug on a spare ignition cable directly to the coil output terminal. Rapidly touch the Black & Black/Violet wires to ground and interupt, telegraph key style ... you should see a good BLUE spark at the test spark plug everytime the ground connection is broken!

You can test your points by connecting the piggybacked Black and Black/Violet trigger wires to the distributor and connecting a 12 Volt test lamp to the trigger wires and ground. As you crank the engine ... the test lamp should flash on and off.

[BK911]

Something to keep in mind for all your future electrical trouble shooting adventures:

Brown is ground, not black.

[Jim_0068]

Originally posted by Early_S_Man
NOPE!!!

The Black wire and Black/Violet wire are SUPPOSED to be piggybacked at the distributor points terminal! Unless they are connected to thedistributor ... engine wont run!

Ok...makes sense however they never were and the car ran previously

Now when you say "points terminal" you are talking about the larger square connector on the side of the distributor closer to where the cap attaches correct?

I guess i can un-piggy back the black wire from the CDI unit and the tach signal and put them where they are SUPPOSE to go and see what happens.

So if i do that (above) the black wire goes to the points terminal and the blk/purple wire is the tach signal right? so it needs to go to the negative side of the coil correct?

thanks

BOY WIRING IS FUN!

[Early_S_Man]

There is only one connector on the distributor besides the high Voltage ignition leads, and that is the points connector ... yes, it comes out the side of the body, and the connector is a bent, male, 0.25" Faston tab!

It would help if you gave a bit more detail as to which version of the '73 911T engine you have??? Carb, MFI, or CIS???

If it is a 'TE' MFI engine then the points trigger wire is also multipled to the MFI Speed Switch.

[Jim_0068]

It is a CIS sorry

The thing that gets me is that i didn't jump the two wires...previous owner did and the car ran. So i don't want to go start changing things all around when it ran fine before.

i'm going to look at it tomorrow probably.

I do appreciate the posts though, i'm sure i'll be back again.

[scarletbegonias]

Hi - I'm trying to solve my no spark problem (1977 911S). I want to try Warren's telegraph test but my distributor doesn't have the black and black/violet wires connected to it. It just has one white wire attached (see photo). Do I use that wire for the telegraph test?

Also - points gap looks correct (0.014"). When I connect a test light to the white wire connected to the dizzy and turn the engine the test light never lights up. Shouldn't it go on/off as the points open/close? Does this indicate a distributor issue?

Thanks

[Walter_Middie]

When I connect a test light to the white wire connected to the dizzy and turn the engine the test light never lights up. Shouldn't it go on/off as the points open/close?

It depends on how you hooked up the test light. The points will ground when closed - so you would have to disconnect the white wire, use a source for +12v on your test light (the CDI unit does not supply +12v to the distributor), and test the distributor for ground. If you did that and the light never came on, then your points are not closing. This can be easily checked without turning over the engine.

[scarletbegonias]

Thanks Rex. I was getting ready to do some ground tests and thought I'd check it on the points first. On the inner side of the points the test light is on and on the outer side the test light is off - even when the points are closed. So I'm hoping the points are shot. New set from Pelican arrives tomorrow, will replace and test again.

[scarletbegonias]

I got the new points installed this evening (wow - I would not want to try and get that points screw in on the side of the freeway in the dark). It started a little rough (it's been sitting since May) and produced a lot of smoke from the tail pipe. Then I remembered to reinstall the hose to the heater blower, but it's still smoking a lot.

It's started right up 3 more times and it sounds pretty good.

I tried to set the points gap at 0.014" but it might not be tight enough. Can this cause all the smoke from the exhaust or do I have to investigate elsewhere?

After winter storage it smoked for about 30 seconds and then it was fine. Now it just keeps smoking.

[scarletbegonias]

Oh - one other difference from before - I removed the air pump down to the check valve.