Starting issue

[liltuber]

OK, so during winter I took out my dash to get some work done to it. I put it back in in a hurry and I dont think I wired something correctly. The problem is with the coil. When I turn the ignition key the starter turns but all it does is crank over and over, no start. I found that the coil wasn't recieving power. If i hard wire a 12v source to the coil it will start right up, but I rather not have to get out of my car and disconnect the coil to shut down the car. I looked at wiring diagrams and everything looks right. I was slightly confused about the tach part and if that might cause it?

Might it be the condenser or resistor?

BTW, It is a 71 240z

Thanks,

Adam

[beandip]

Look for the black/white wire coming from the tach to the ignition. The tach must be in the loop, or the ignition wont fire. Gary

[Nissanman]

The tach must be in the loop, or the ignition wont fire.

The factory tacho. is an impulse type and detects the primary coil current impulses when the ignition points operate.

It is in series with the primary circuit, any discontinuity here and NO GO:disappoin

Watch the tacho. when you attempt to start the engine.

Usually you will see it kick and read the cranking rpm.

If no joy then the tacho. is indeed "out of the loop".

[liltuber]

Thanks guys. I didnt have a chance to work on the z today. Advice sounds great. I know I have a 3(I think) wire clip plugged into the back of the tac. Is there supposed to be any other wires coming out of it?

Also, I have a mystery part I was wondering if anyone knew what it is. Its a shiny cylinder about 4 inches tall and about an inch diameter. It has 2 electrical posts on the top. Its located behind the dash tucked behind the gauges.

Adam

[sblake01]

Sounds like you're describing the illumination rheostat for the guage lights.

[liltuber]

Ok, so get this. I went to test the tac and as i cranked i heard an occasional electrical poping sound. I had forgot to reattach one of the external resistor wires from when i was testing wires with my ohm meter.(Unplugged it trying to solve the issue, so this wasnt the solution) Once I plugged that back in I noticed the tac was moving. Then, the car started briefly! It was acting the way it was when I thought I blew up the old coil. It would start just long enough that i had to to the key to on, then i would sputter and then stall. Barely would rev up or anything.

So what would cause the car to begin to start and then just drop off? Might it be the external resistor having a poor connection?

Adam

[liltuber]

So i picked up a new condensor and guess what... that wasnt it. So, if the ballast resister is going out would that cause this? When the key was in the on position the resister got really hot after a while. Bad?

I read a while back that if the vacuum thing on the distributor(sorry, brain fart) goes out, it runs like crap. What happens if that goes bad?

Adam

[JimmyZ]

I'd start by inspecting the faces of the points and point gap. As a temporary test you could run a wire from the battery "+" to the coil + terminal. Be careful you don't short your jumper wire. It gets hot and if over a fuel line... Use your imagination. If the engine isn't turning and you have the coil on you will burn your points. At that "point" you'll need to sand the point faces or better yet replace the points. A set of sanded points will decline in performance quicker than new ones especially if they are the common/cheap plated kind. (Will get you through 'til next paycheck )

Restating above->When using the key or a bypass wire you should never have the ignition (coil) on unless the motor is cranking. You will burn the points. You can burn up a points rated coil by operating it at 12 volts. The time it takes to kill a coil depends. It could take a few minutes to a few weeks.

A bad vacuum advance won't keep it from running.

There is a way to bypass the tach with a jumper wire but it's kind of a PITA. Tach has to come out to see/work with wires. When I bought my Z it had this done until I could get a JY tach.

[Nissanman]

If the car starts when the key is in the START position but dies when you move it to the ON position then it usually means that the ballast resistor, or the connections to it, are faulty.

The ballast is bypassed by ignition switch contacts when you START and switched in to circuit when you are ON.

[liltuber]

JimmyZ the car runs great if i bypass the ballast resistor and just run a 12v source to the coil. When I first figured this out it probably should of thrown a flag, but hell, im no electrical engineer. The points are still nice and pretty because its a relatively new cap.

Nissanman, I'm thinking it is the ballast resistor as well. A couple nights ago I swept every forum I could find, and on a jeep forum they said the same thing you did.

I'll get a new resistor and let you guys know.

Thanks,

Adam

[beandip]

The points we are referring to are not in the cap. They are down in the dist, and have a rub against the center pole of the dist. these contacts open and close with the 6 lobes on the shaft. They look like a small lever with round flat tips that come together and separate with the action of the connection to the main shaft as it turns. If you keep 12v going to the ignition it WILL burn the points and they may even weld themselves together. This is about as basic as I can describe them.

[liltuber]

Ah yes these points. Wow. Well I guess the reason I posted on here was to get some help, so i'm trying not to feel like a retard.

I tested the resistor and it measured a resistance so then i took a file to these points and I bet you can guess what happened. I'll give you a hint. I bought a new contact braker plate shortly after.

Thanks for all the help guys.

Adam