charging issue? not sure where to look...

[Haaland]

Hello everyone.

In my 66 I'm running a 283 with a TBI unit and edis ignition. I know it's not the normal engine build here but, I'm now in the tunning phase and can not run more than 12.6 vdc. I just replaced my alternator today with a 12si it's rated at 15.8vdc 94amps I bypassed the external voltage regulator and still, from idle to 3400rpm 10.5 to 12.6. I have disconnected everything besides the starter, ecu, fuel pump and ignition module. Is there somewhere I should start chasing this problem?
Any advice would be very appreciated.

-Alex

[Nanook]

Where are you checking the voltage?

Are you checking at the battery or directly on the alternator?

[Haaland]

I had my multimeter hooked up to the battery and then my ecu takes power from the switched hot side of my fuse block ,and grounded back to the battery terminal. I've found no ground or any reason for voltage drop. I'm thinking my pulley ratio may be too low not allowing the alternator to spin far enough?

If the battery was bad the alternator should work harder to try to charge it correct? I feel like I have tried everything and I'm just throwing out random ideas now.

[chevy_mike]

You want to check the voltage at the alt. output post. This is what the alt is putting out? If it's not 13.8 or higher then it's not putting out the correct voltage and could be bad (yes even new they can be bad). That that is okay and you are getting less then that (like the 10-12 volts you are saying) then you have a wiring issue somewhere.

How did you bypass the external regulator? If you have a 3 wire alt then you need a sense wire hooked up so it knows how much voltage to output. If you bypassed the external regulator incorrectly, that could also be why you are not getting enough voltage.

[Haaland]

For some reason I can not load the picture or find the link to what I used but it was on this form. Blue wire is jumpers to the red wire and the white wire to the brown wire on the plug for the external regulator. White wire goes to pin one on the alt and blue goes to pin two if that make sense?

[VetteVet]

Originally Posted by Haaland

For some reason I can not load the picture or find the link to what I used but it was on this form. Blue wire is jumpers to the red wire and the white wire to the brown wire on the plug for the external regulator. White wire goes to pin one on the alt and blue goes to pin two if that make sense?

The guys are right with their advice. You jumped the wires correctly. You probably saw one of my threads where I posted the conversion jumper. You won't need the ground wire but it won't hurt to leave it.






Here is how I do it, it eliminates the regulator and it's harness. You just run the brown wire directly to the alternator to no. 1 and the red wire to no. 2.




Check for power on the brown wire. With the key on you should get 12 volts and with key off you get 0 volts. The red wire will always be hot, 12 volts. You should get 13 to 15 volts on the alternator output wire.

[Haaland]

Thank you everyone!
VetteVet your thread was the one I was looking at and yes I had it wired wrong. Also I had changed my dash the same time I changed the generator to an alternator. And did not have the dummy light wired in. The old externally regulated alternator probably stopped working after I changed the dash but i took the truck of the road so never noticed.

Now I have the red wire going directly to no.2 and blue wire is still going to no. 1 with my dummy light jumping it to the brown wire.

The dummy light came on with the key on then turned off once the truck was started.

Alternator was still only putting out 12.6vdc.

[VetteVet]

Originally Posted by Haaland

Thank you everyone!
VetteVet your thread was the one I was looking at and yes I had it wired wrong. Also I had changed my dash the same time I changed the generator to an alternator. And did not have the dummy light wired in. The old externally regulated alternator probably stopped working after I changed the dash but i took the truck of the road so never noticed.

Now I have the red wire going directly to no.2 and blue wire is still going to no. 1 with my dummy light jumping it to the brown wire.

The dummy light came on with the key on then turned off once the truck was started.

Alternator was still only putting out 12.6vdc.

The alternator is charging but it should be putting out at least 13,5 volts at idle or it can't charge the battery. Check the blue wire for 12 volts at the alternator. Normally you would jump the brown and white wire but it shouldn't matter as long as the brown wire is going to no. 1 and the red wire is going to no. 2. If the no. 1 wire is less than 12 volts the alternator won't put out full charge. I suspect that the internal regulator in the alternator is faulty if you get 12 volts on the no. 1 wire with the key on.

[Haaland]

Thank you. I had to take a couple days off, but I will get a new alternator this weekend and give that a shot. Just to make sure I have everything 100% correct and understand everything.

Wire no.1 goes to the dummy light then to switched 12vdc?
Wire no. 2 goes to constant 12vdc?

[gmachinz]

If you need a 5.25" cased alternator and have 12 and 6 clocking, I'd suggest ditching that SI and instead go with a CS version instead. Wiring is the same as what Vette has suggested for you except the alternator connector is different (you can get it at any parts store) and you'll need to swap pulleys-that's it. Tell the parts guy to pull down an alternator from a 1988 Olds Firenza with a 2.0 FI 4 cylinder engine. It's rated at 90A as well but is FAR more efficient at stabilizing system voltage than the SI.
For people wanting to appear stock this is the ideal alternator to run on non serpentine, v-belt GM accessory drives IMO. I've done countless swaps on 68-72 A-bodies using that very alternator. I'd also suggest doing a system upgrade on the charging supply leads as well while you're at it-never hurts to set it up to get the absolute most out of it. A lot of people think 250-300A alternators solve all problems when in reality it's usually a lack of properly supported wiring that chokes off high amp alternators capability....this includes all versions of the CS familiy of alternators.

[Ewr101]

I agree with GMACHINZ and VetteVet. I upgraded from the stock externally regulated alternator to a CS140. Upgraded all the wiring at the same time using 8 gauge wiring for the alternator/junction block/battery run. Now I got plenty of power and a way cleaner engine bay! Went from 12.6-12.9vdc at the battery to 14.4vdc.

[Haaland]

Vettevet, Gmachinz and Ewr101. Thank you I have some 8 gauge wire in the garage I will install today. I took the alternator back to Napa they tested it and it was not putting out voltage. I do like what I read on the cs alternator but right now I'm just trying to get this old 283 up and going until I find the engine really want to use, between an lsx or vortex 383 with mpi.

[Haaland]

Thank you everyone! For the new alternator in today and I'm getting 14.4 at idle from the alternator it's self and at the battery. My wiring was wrong at first I is not have the exciter light in, also I changed everything over to 8 gauge. Thank you so much now I can actually start tunning this thing.