vze2jshn

Car will not start. No spark. Jumped to replacing coil and green wire because I had them on the shelf. Still no go. With ignition key on I get only 1 volt at 15 + terminal of coil WSM says I should have 3 volts.I will check voltage at 0.4 ohm resistor and compare to voltage at battery while cranking tomorrow per WSM. Question: Should terminal at 0.4 resistor be so hot as to radiate heat and cause blister on finger with ignition switch on? Any comments, insights are greatly appreciated.

systemsc

While cranking, the positive terminal of the coil (from the resistor) should have at least 8 volts.

Mrmerlin

What brand of green wire do you have ?

did you have to force the connector into the distributor to be able to put on the anchoring plate ?

Note the resistor is made to reduce the amount of voltage flowing through it

As a function of this event heat is created the amount of heat is enough to burn your finger

Put deoxit 100 on the wire connections to assure full current passage

systemsc

The resistor is typically bypassed while cranking, i.e. the full battery cranking voltage is applied to the coil.

vze2jshn

Thanks Mrmerlin and Loren. I have cleaned all connections and I still do not have sufficient current to the coil. So I am searching for the current drop. I am Confused by the representation of the starter relay in Alan Moore's fuse/ relay chart which lists two part numbers for starter relay. Can I swap in another 928 615 117 00 from the horn for example to see if the starter relay is at fault?

Rob Edwards

Do you have a stock starter with the three wires connected like so?

Rob Edwards

Good description of the '78 starter connections here: https://rennlist.com/forums/928-foru...ry-1978-a.html

systemsc

Yes, especially post #6!

vze2jshn

Thanks guys I've reviewed all the great info you have provided including adding the jumper cable ground connection. I have traced the black/yellow wire back to the starter connection where the voltage reads 1.5 volts while cranking, the same as at the 15A wire on the coil ( it should of course be around 12 v at both places). So I am concluding that the connection on the starter solenoid is bad and I will replace the starter. I may try to run a wire from the hot nub under the hood to the black/green wire on the resistor and try to at least get it started so I can get to a lift at my friend's repair shop. Lying on my back under the car in the garage to replace the starter does not appeal to me especially at 76 years old. As usual any comments, insights are greatly appreciated.

Mrmerlin

what voltage do you get at the coil get with the key in the run position
Are you aware of the neat wiring trick they did so the starter can be energized with the key placed into the run position,
thus making it possible to start the engine without cranking it with the key?
TO do this follow these instructions.
make sure to set the E brake.
Put the trans into neutral or park,
open the hood,
then separate the 14 pin connector at the hot post.
Identify the pin closest to the front and closest to the right fender,( this is the 50 wire)
NOTE touching this pin to the hot post will make the starter run.

Go turn the key to the run position.
then touch this pin to the hot post,
the engine will crank and it should run.

NOTE connect the 14 pin connector carefully and secure the hot post cover
Close the hood and drive away

vze2jshn

I get 1 volt with key on at the coil. The car cranks with the key but I do not get the required voltage for spark at the coil. There is no or very little power to the black/green wire from the 16 terminal at the starter while cranking. Will your solution provide the necessary 12 volts or so to the coil through the black/green wire and hence spark and start up?

Mrmerlin

What was the last thing that you fixed?

you could try my suggestion,
but with the key in the run position you should have more than one volt at the coil.

vze2jshn

Correction to my last post: Wire from terminal 16 at starter is black/yellow not black green. Getting a little batty here.

systemsc

Hopefully, the ignition box output is not shorted to ground. Disconnect the ignition box and measure the coil voltage.

vze2jshn

I have tried all your generous solutions to no avail. As I mentioned earlier, I did not have the required 12 volts to fire up while cranking at the black/yellow cold start connection at the starter so I decided to replace with a new or rebuilt starter. No new or rebuilt bosch or other usual suspect starters were available supposedly due to the Ukrainian conflict. I did source a new denso (Wosp) high torque starter at a surprisingly reasonable price which would not mount properly because it has a 11 tooth nose rather than the required 9 tooth set up with my ring gear. Reinstalled old Bosch and disconnected cold start black/yellow wire and car cranked and fired up! I have since received a 9 tooth nose from Wosp and will be fitting it to the new starter. I will then put new starter on when I have access to a lift at my friend's repair shop and will probably have old starter internal solenoid connections addressed- don't really trust it at this time. Thanks again for your considerations any additional comments are greatly appreciated.