alternator instillation problem
 

I installed a new alternator after having the old one fail on me. The new one has the internal regulator on it. Purchased from our host. I put it back in just the way it came out, I believe, however, I am not getting the car to start. We're talking a 1977 911, 2.7 coupe. I had three connections to make plus a ground strap. Looking in to the alternator, on the left post, the + side, goes two red wires, on the right side, 3 brown wires, on the center post, most highest, looking in, a blue wire. The ground strap, connected on one end, is to the block. I connected it to the alternater housing. After putting it all together, I connected the lead coming from the coil to the coil holder. I checked for spark and don't see any coming from the coil wire. I am getting gas. The battery is charged. Disturbing to say the least. Any reasonable ideas or suggestions will be appreciated. The alternators are the same numbers 911 603 120 04. Could I be shorting out somewhere?

Are you getting 12volts to your coil? you may have pulled a wire loose on the coil.

alternator
 

I'll just don't understand why that would happen if indeed that is the case. I will check. Thanks for the tip. I will keep looking and wondering.

To pa911, and others who don't have a clue about the operation of the Bosch CDI system:

<b>CDI systems NEVER HAVE +12 Volts at the coil!!! One side of the coil is permanently grounded, and the other side gets intermittent, timed +460 Volt pulses from the CDI unit!</b>

michigan,

To test the CDI system plug a spark plug wire directly into the coil and ground a new spark plug for testing purposes. Disconnect the Black and Black/Violet wires at the distributor and repeatedly touch the Black wire to ground. Each time the wire is lifted from ground there should be a blue/white spark at the test spark plug.

michigan,

I have the alternator out of my 1975 2.7 - I think the wiring should be the same as a 77 - maybe one of the experts can verify this. The picture below shows how I am planning on hooking up the alt. Note that the top of the alt. is at the bottom of the picture. The blue and red wires connect to adjacent terminals, with the blue wire just to the left (drivers side) of center - or to the left of the very top of the alt.

http://forums.pelicanparts.com/uploa...1125757797.jpg

Hope this helps - Rex

alternator
 

Rex, My alternator is different than yours. I wish I knew how to post a picture to show you but, I don't. Suffice it to say that they are different. What would be the alternator numbers on yours? The terminals are similar in location but, there are suttle differences that I can note as I look at your picture. Thank you. Early S man. Thank you for your knowledegable input. I will do just that and let you know how it goes.

Hey your right there's not 12 volts at the coil.:rolleyes:try doing a search on alternator wiring.

alternator
 

OK. Here's my rational on the matter. Should'nt the car start and run regardless of if the alternator is hooked up wrong or right. If it is incorrectly wired on the terminals, could that cause it to short out the electrical system and not allow a spark? In theory, you could go without the alternator putting out a recharge of electricity to the battery until the battery runs out totally and, even then, the engine would still keep running until you shut the engine off. Am I right on this?

I wanted to bump this up because I still don't have any answers. Any input will be appreciated.