Hello friends. I've just as of last night May 1st got my SA running after a year and a half of building. It's got a freshly rebuilt 13b fc engine with a 48ida weber, fully built suspension, etc etc. New battery (relocated) new cables, upgraded alternator. The car started and ran great!! But i'm now having some issues.

1. What makes the voltmeter/tach go from a working voltmeter to working tach? when i wired in the s4 alternator, i ran a new 8ga wire from alternator post to battery, and then in the regulator plug used to jumpers to jump 4 pairs of wires, resulting in 12v+ to the s4 alt top terminal and ground to the lower terminal, so I have a working alternator.

2. started and shut it off maybe 10 times yesterday, on the 10th shut down I turned the key to off and it stayed running... unsure of why that happened as of now (it was 10pm)

3. no turnsignals or hazard lights, haven't looked into this one at all yet.

4. when i first hooked up the battery and tested the lights, the headlamps would come on but not flip up. they would sometimes with the switches in the center console for "up and no light on" then they finally started working correctly.

Sounds like the next step is to clean all the connections super well, but not too sure of the volt meter thing. Fuel gauge and coolant temp gauge seemed to not be working either, there's only 4 gal of gas in it though.

 

1. I'm using stock ignition for an 82-85 car, with FC plugs. Should i be using plugs for a gsl-se or 12a instead?

2. Since it's a weber, i don't have a ported vacuum source. Currently my vac advance pots are open to atmosphere... I can put them to manifold vacuum easy, but does that even matter? Seems to me it would only use vac to advance at idle.

 

The volt meter on an SA relies on connections to the choke and check relay which is located up on the
driver side inner fender opposite the brake master. The FSM electrical diagram can help you sort out
whats needed. This relay also makes all your lights test out on the console when you turn the key before
starting.

https://www.autopartone.com/collecti...em-check-relay

Some info on the wiring for the relay:

SA22C Digest V1 #1099

 

Choke and check relay i left original, i added a plug for the alt, and then jumped two pairs of wires in the regulator like i read on here. bottom post i have gnd, top post i have switched 12v+. When i shut the car off it stays running, fuel pump stays on. If i unplug the alt the car and pump shut off. The alt is back feeding somehow... but all my wiring seems right. The only wiring done to this car is for the elec ign and the newer alt.

 

Be careful wiring an alt, its easy to fuxor the internal regulator. Recheck wiring and compare to FSM
wiring diagrams. Somethings not right for sure.

 

So i checked and rechecked all my wiring.. the key when turned to on, sends 12v+ to the alt, when the key is off it sends nothing to the alt. like it's supposed to.. the bottom post is ground like it's supposed to be.. everything checks out with a volt meter using the factory wiring diagram. everything. is it possible my alternator is bad, causing it to back feed the ENGINE fuse?

If i could get the car to shut off without pulling a fuse and get the turn signals working it would be much nicer to drive around

 

Believe i can help you fix the alternator"feedback" issue. Leave everything as is,start car,verify alt is charging battery @14.2-14.5 volts,yes?
With car still running,put voltmeter probe to 12+ wire at alternator. Should be showing close to what battery charge voltage is 14 volts+. Turn ignition off and watch what voltmeter reads at 12+ alternator feed,should be tenths of a volt. If it shows 10 volts or higher(likely will be the same 14 volts) you'll want to install a diode in that circuit to allow ignition switch to feed voltage to the alternator to excite it to charge but not allow voltage regulator to power the ignition system when key is turned off. I'll give you the info on diode when i can get a minute.

 

I Upgraded my SE to modified S5 alternator a while back and had a different issue with a slight draw on battery but the fix for yours will be the same. After i dealt with this i found a thread on here addressing this several months later. Radio Shack 1N4001 Diode installed inline of feed circuit,close to alternator is best. You can hook into system with jumper wires for test purposes,try to duplicate the problem. If all good,solder and heatshrink into harness,call it done. Use a heatsink while soldering diode in,they don't like heat. You can have someone hold diode with needlenose pliers if you don't have a heatsink. Now you can drive the car. Post back with results.

 

That all makes sense, but when i was hooking up the alt i tested the wires I put into the 2 prong plug. 12V+ switched on and off with the key and the bottom pin is ground. Seems to me if that's working the problem would be internal in the alternator? Installing a diode would fix the issue, but still seems like the alt is broken. Or am I completely wrong? at idle it's showing about 14V+ charge

 

If 14 volts charge you're referring to is read at battery,alt is functional. S4-S5 alternators come from fuel injected cars and as such their wiring harness and method of feeding exciter voltage to alt internal regulator is different. Had you left car sit for extended time you would come back to a low/dead battery as the regulator in alt will not shut down fully with S1-S2,and some S3 cars with their original wiring. Very likely alt. & wiring is fine,if all wiring to and from ig. switch is as it should be,the diode will fix the "issue". This is not a band aid fix,just a mod you need to do to run later model alt. in your car. Done this to several FBs that are running fine for some time now.

 

Forgot to add,you're going to want to fuse the alt. output wire as the way you describe you wired it seems to be unprotected. I would run 1st gen plugs as easier for stock system to fire them than 2nd gen plugs,or you could do a direct fire conversion to run the other plugs. In some experimenting i've done i found 1st gen NGK plugs with DFI seem to work better than 2nd gen plugs.

 

The s4 and 1st gen alternators are plug compatible I thought. I installed an S4 in my SA with no issues,
keeps a good charge and doesn't leak down that I have observed.

Maybe you blew the internal diode in the alt while getting the wiring right. So the diode may fix it up but
getting the alt tested might show if its internally messed up. Not discounting the advice GSLSEforme has
provided as it sounds right for fixing the issue.

 

tg, they are a bolt on in every way. Don't believe i've had this problem with an oe unit. The ones that exhibited this trait op has the problem with were all rebuilt units,load tested with a carbon pile tester right about where rated,no ac ripple &charging cutout voltage @14.2. No performance problem with alternator. Had occasion to have an FC reman apart just out of warranty to replace a noisy drive end bearing & noted internal regulator was different design than oe. Rebuilder put in an aftermarket one as original likely failed. My thinking is the replacements circuitry is different(cheaper)than oe and may explain this issue with some reman units.

 

The FC alt. like a lot of others has a diode bridge with three + diodes and three- diodes. Op states charge voltage at idle is 14v.
If any one of the six diodes is defective,alt.output is reduced by 1/3 & very unlikely alt.can put out 14volts at high rpm let alone at idle
speed so i'm thinking his alt. is fine & diode install will solve the problem he describes.

 

I probably got lucky with mine. Makes sense to me.

 

use a 6amp diode from radioshack (2761661), 4 diodes in one pack. theres only one way to install it so the colored or stripped side faces the alternator and be sure to heat shrink the entire diode and connections. diode will prevent the engine from running even with the key off. just like you, i went thru this experience for a few days til my neighbor mentioned this solution