electrical/charging system???

[FuriousCJP]

I have a 1984 318i manual coupe w/ M10. To get some of you up to speed I had a electrical problem---low voltage, bog/ sputter, smell of fuel, dimming dash lights, and rpm needle bouncing-dropping to 0-then bouncing again 2nd. All of the 2nd issue was intermittent. Changing plugs, wires, coil, and running Lucas fuel treatment thru helped some but still intermittent prob. Well the car ran good till about May/ June. I found it dead 1 morning so I leak charged it. Started an ran fine. I hooked up my multimeter 2 battery so I could watch batt voltage while driving.

[FuriousCJP]

I noticed it started dropping again on way to my 1st job. It died that nite right in front of my 2nd job. Got a jump after work and it died again( while driving), had to tow home next morning. Leak charged it and it ran great for bout a week. I really wanted 2 just go get alternator right then but I ran into many unexpected expenses for a few months. My thought was the winter was extremely bad so the old alt probably crapped out and was killing batt as i drove. I drove it like that till September. Only driving 20-30min drive to work and back( x 2 jobs).
I've been sharing a car w/ someone and getting rides since Sept. I did notice something while driving it for those 4mnths. The batt lifetime may have differed but it was always drive, charge, reapeat.There was a few instances tho where the volatage would drop way low( maybe i forgot 2 charge it, etc) while driving and bog/sputter, lights dimming, rpm dropping to 0, almost dying. Then all the sudden it would come to life. idling/running, rpm, lights ALL FINE?

[FuriousCJP]

So 1st thing that came 2 mind was loose ground. Now i wanna hunt down all the grounds. What else has a ground besides battery, alternator, and starter?? Any other ideas or input would be a great help.

[estoguy]

Have you checked the voltage regulator? A lot charging/alternator problems can be tied to them getting worn (it is a wear part, doesn't last forever). I had a similar thing happen to my Eta.

10-15 minute fix.

[TobyB]

Yeah, worn- out brushes (part of the regulator) can do this- they'll make contact for
a minute or 3, charge a bit, then lose contact.

I personally am a big fan of the self- serve junkyard...

t

[FuriousCJP]

My apologies for the long gap in post. Got the batt. tested and it tested bad so now ive got a new/used one in it. I've got the new alternator at home and plan 2 put it on this weekend. Im hoping thatll slove most of the starting/running issues. Afterwards i plan on checking over the rest of the ignition system via the test in the bently man. I would also like to check the fuel pressure.
My new ? is this. When i got the car the PO had blown fuse 21 to the point where the slot in the fuse box is melted and i cant get another fuse in there. Ive looked at what fuse 21 runs and didnt see anything too important. You guys think ill be alright w/o it?
One more thing struck me as wierd. When searching the forums i found that the Tach/fuel economy gauge shouldn't work if fuse 21 is blown. BOTH MY TACH AND FUEL ECON GAUGE WORK My interior lights will work from time to time not to mention the clock always comes on (but doesnt hold memory).
I thought none of these would work without a fuse. So will i be alright w/o fuse 21? If not can i bypass it maybe via a jumper wire with an inline fuse? And do u guys think this has anything to do with my past power drain/ heater issues( being fuse 21 is right next to the heater fuse 20)?

[FuriousCJP]

I got the old alt off and noticed i was missing the ground wire that goes to the throttle body (G101). Right next to the cold start. Now im not even sure if i had one when i got it. I could not for the life of me find a loose wire anywhere. I tried to look in the bently manual but it really wasnt telling me the fro and to of g101. Finally found a wire diagram: https://html1-f.scribdassets.com/94t...4ed335363f.jpg

Now to me that seems like a major issue. Theres a crap ton of things ground out by g101. What could this have done? and what could this be doing to my car? also where could i splice a ground wire in to get all these components?