911 died on the freeway

[scoll911]

I'll start by stating I've spent the last 4 hours searching this forum for answers. I have a 78 3.0 and the car turns over but no start.

I'm not hearing the CDI whining noise. I turned on the ignition and used a test light on the CDI connector and none of the pins lit up. I have an 8 pin CDI unit. It seems most of the posts speak to a 3 pin set-up???

What should I do next any and all help is appreciated

Thanks

[Zeke]

First, you check fuses. I think you have a 6 pin CDI. 3 pin were earlier, AFAIK

[w21055]

Check fuses. Does the dome light work? I don't think it is a fix for the 78 but my 80 blew that fuse and mine would not start.

[scoll911]

I checked the fuses one was bad I replaced it and the moved the wire asthe block was bad. Still won't start, I still do not hear the whining from the CDI. I assuming you meant the fuses in the front. Any other ideas?

[Formerly Steve Wilkinson]

Funny, I just had our Boxster flatbedded when it totally died. Turned out to be a fuse. Dumb.

[Paulporsche]

If it is a Bosch CDI it should whine if it is OK; if another brand, then it won't whine.

[unclebilly]

I have a cdi unit from my 77. Let me know if you are interested.

[Gunter]

Originally Posted by scoll911

I'll start by stating I've spent the last 4 hours searching this forum for answers. I have a 78 3.0 and the car turns over but no start.

I'm not hearing the CDI whining noise. I turned on the ignition and used a test light on the CDI connector and none of the pins lit up. I have an 8 pin CDI unit. It seems most of the posts speak to a 3 pin set-up???

What should I do next any and all help is appreciated

Thanks

The pump may have failed.

If it's a '78 SC, you should have a Bosch 6-pin CDI module. (8-pin is for turbos) A 3-pin from a '77 will not work on SC's.
Be careful with using a test light on the pins, the CDI is sensitive.
Terminal 15 should have 12V.

Not all modules whine.

Check the 3 fuses (2-25A, 1-5A) in the REAR fuse panel; one of the 25A gives power to the module.

The Bentley SC Repair Manual will give you direction to trouble-shoot the CDI.
If you don't have it, get it.

A no-start could be fuel, ignition or a vacuum leak.

To check fuel supply, remove the air filter and lid.
Turn ignition ON.
Reach into the airbox and carefully lift the Air Sensor Plate VERY BRIEFLY.
You should hear the injectors squeal, release the Plate.
That means the pump is running.

Next check for spark.
(A 3-pin from a '77 will not work on SC's)

Get the Bentley.

[scoll911]

Thanks guys, I plan on checking all of those shortly. Will keep you posted

[scoll911]

Just tested the engine compartment fuses and the bottom has no juice (according to the test light) ignition on and off.

[Zeke]

Could be your ignition switch. That is if you don't have 12v to either side of the rear fuse. They've been known to fail.

[scoll911]

Ok, I just tested pulled an injector and tested the system and I did not get gas. The way it stands now
My bottom fuse of the 3 does not have juice to either side (not sure if it ever did)
Not getting fuel to the injectors ( I have an extra fuel filter wondering whether I should toss it in).
The third fuse in the trunk which looks lioke it is attached to the fuse relay harness is not getting juice to either side (see Pics).


As the fuse next it was fried I moved it to an open spot. Any thoughts?

[scoll911]

I tested at the box and through the wires and no juice either way.

[scoll911]

I tested the fuel pump posts with a multimeter with the ignition and a jumper between 30 and 87a (also with relay in). the meter did not pick up any volts at the posts.

[snbush67]

Switch your red and black round relays and see if you can get some gas to the injectors.

[scoll911]

The latest
The attached picture shows a cable going into fuse 3. This cable does not have power (ignition on nor off). The cable is spliced with one red wire leading to the fuel pump relay and the other leading off to the left somewhere??

• Question what powers this line, is it a feed from the ignition switch?
• Does this wire power the fuse box or is it brought in from somewhere else?
• Should this wire have power at the fuse box? If so should I try to power from another fuse?
• I dont think it is the relay as I don't beleive the there is power going to the relay. How do I check this?

I don't have a bentley manual, so whatever you can upload (diagrams, etc.) what be appreciated.



I used a test light and there is no juice in either wire.

As usual any help is appreciated as this is my daily driver.

Thanks

[tmctguer]

do you have spark?

my '73 911e died suddenly on the freeway and it turned out to be a bad ignition coil.

[scoll911]

Could someone post the wire diagram from the bentley? I did a search and can't seem to find one for my 78.

[Gunter]

If you are serious about doing some work on your SC, you'll need the Bentley.
The Bentley has 30 pages of electrical diagrams starting at 270.
Aside from the Lambda stuff for '80-'83, the rest is the same for '78-'79.

Wow! I just looked at the pictures.

Someone did a terrible hacking on this SC and nobody is going to know how to solve the mess because it's definitely not stock.
One of the worst hack-jobs I've seen. Where are the relays?
You'll have to decide if you want to restore the wiring to stock.
How else can anyone know which wires go where?
Whatever the PO intended in the past leaves you with some real problems.

This is what your front fuse panel should look like:



Ignore the extra head light relays on the bottom; the rest is stock '80.

[scoll911]

Gunter,

Thanks for bumming my high (lol). I will get the book, but I was hoping this would be a quick fix and I would get this up and running fairly quickly. Yeah, the PO screwed up a number of things. I've owned the car about 10 years and although I've rebuilt the engine, I've been reluctant to mess with the electrical. I guess it is tme