electrical and ignition Starting/Electrical Power issue

[p1k]

I've read through recent posts of cars not starting, and took from them as much as I could to come up with the information I currently have. My situation seems to be a bit different, this is whats going on:

 

I haven't driven the car in 3 or more months. Its a rebuilt m10, 9.5 pistons, 292 regrind, weber 38, no real ignition upgrades but the motor was in good running order prior to parking. I went to start the car and didn't get any power/lights in the cluster, so I first bought a new battery since it was about that time anyways. Purchased a new 26r prime start from sears. Brought the battery home and fired the car up no issue. I didn't run the car long because I had a small coolant leak in one of the heater hoses, but shouldn't change anything. Then I didn't touch the car for another 2 months. I came out, tried to start the car, it cranked and cranked and cranked but didn't fire. Then the car lost electrical power. I assumed I cranked the now smaller battery than the previous which I am pretty sure was a 42 but irrelevant at this point, dead. Didn't think much of it, so I put the battery on the charger and came back to it again, with my roommates car to assist the battery with a jump. We sprayed some starter fluid in the carb while cranking, and the car turned over normally without starting multiple times, then slowly lost power again, until the motor was only turning over once every second or so. Then once again I lost all power to the instruments, the headlights, everything. 

 

So now I tested a few things (hopefully correctly)

These tests were all done once the car wasn't able to crank over anymore and didnt have any electrical power in the instruments

My battery reads 12.8v (full charge) + its new

Terminals are clean, and the grounds are ground tightly

The starter is getting the same 12.8v, but with the key in the ignition in cranking position the starter loses all voltage.

The #15 terminal on the ignition coil is not giving me any readings on the multi-meter with the key in both on/off positions 

 

I looked through my blue books to find which terminals are what in the ignition switch and when i tested the Red wire (battery#30) that read zero, as well as the starter wire (black#50) read zero with the key in the start position. 

 

So currently I have no power to the dash instruments, headlights, or anything with the key in. But my battery is fully charged.

 

Im not very experienced in diagnosing electrical/starting issues but Im hoping this might be enough information to point me in the right direction. Seems to me the ignition switch is at fault, but looking for others opinions or more tests I can do to narrow it down.

 

Thanks 

Tim

 

[M3M3]

have you bypassed the seatbelt interlock relay yet?

[M3M3]

http://www.bmw2002faq.com/topic/93425-how-to-bypass-seatbelt-interlock-system-on-1974-bmw-2002a/

[p1k]

have you bypassed the seatbelt interlock relay yet?

 

I just looked up the how-to. 

My car doesn't seem to be wired for the interlock. I was able to trace my starter wire from the ignition switch all the way to the firewall.

[esty]

a long shot but check all your fuses...

[Son of Marty]

There should be a 2nd smaller positive connection that connects to the large positive battery clamp make sure it's clean and tight there is also a small ground wire from the neg terminal to the body to check.  

[Solarphil]

when you say you tested the voltage and saw zero (in a couple places) what was the position of both meter leads -- voltage is usually a measure in relation to another point in the circuit.

Also, what is the battery voltage at the moment when you hit the starter? If the battery is hanging at 12-12.8 when you are losing power to lights, dash, and the starter is cranking once per second you have a wiring issue, check the items in the posts above. If the battery voltage at its terminals is collapsing to the point the lights cut out (usually sub 10v) you have a failed cell in the battery. But I doubt that is the issue.

[p1k]

There should be a 2nd smaller positive connection that connects to the large positive battery clamp make sure it's clean and tight there is also a small ground wire from the neg terminal to the body to check.  

 

This was on the money. I originally looked at all the power connections, wiggled them and inspected for corrosion. I wasn't able to see anything obvious, so I thought it was my ignition switch because I turned the key and the result was no power, or dash instrument lights. I changed that, no dice. I also ran an extra ground to the block from my alternator, and checked for the seatbelt relay as mentioned before. I cleaned the ground from the block to the battery and the multiple grounds that mount next to the relays to no avail. I went back last night after looking through the wiring schematics and decided to test the red power wire right off the battery that goes to the ignition and it showed very low and fluctuating voltages. Since I thought I originally checked the power wire and since it was directly connected to the battery I assumed it was all good and working, wrong. I cut the wire down, stripped it, and put a new connection, mounted it up and the old turd fired right up. 

 

So for future reference, if you aren't getting any power to your ignition switch, no lights, no action. Check the solid red ignition wires connection to the battery. Hope this may help someone in the future. 

[M3M3]

yeah!  

 

thanks for closing out the problem solution for future searchers!