wph351

iTrader: (3)

Well it's not the gauge. After swapping the wires as mentioned above, I only had 12.6v feeding the gauge. At the battery 13.7. These readings were taken after a drive, with the car hot and in idle. Had 14.6v at the gauge AND the battery at start up, and during a 2-3 minute warm up period before the drive.

I'm running multiple circuits off of a 4th gen ignition relay. First thing I'm going to check is voltage in, and voltage out of that relay. Cold and hot. Will report back with updates.

00pooterSS

iTrader: (40)

you could do a quick test and pull the relay and jump the two pins with a paper clip or piece of wire and see if the voltage changes, or test in and out as mentioned. Typically with a GM you have pins 85,85,87 and 30 on the relay and you'd jump 30 to 87. 85 and 86 being the relay control pins.

wph351

iTrader: (3)

Yep that's pretty much the plan. Anybody know what amp these relays are rated at?

00pooterSS

iTrader: (40)

Would have to know which exact relay you are referring to. Not sure if you're using the old setup, new swap setup, custom.... You'll have to search the relay part number man.

wph351

iTrader: (3)

I'll have to pop it out and check. Although I believe it to be the original ign. Relay from my donor vehicle which was a 2000 f body

chrysler kid

iTrader: (14)

Just run the feed wire for the tester on its own relay directly to the battery.

Otherwise you can test draw on the system by pulling fuses to determine where the voltage drain is coming from

I've mentioned it a few times and others have noticed the dash gauge is not accurate anymore like when the car was new.

00pooterSS

iTrader: (40)

Is your volt gauge a 2 wire or a 3? If it's a 3 one may be a turn on or trigger wire to turn the gauge on and you could use that to connect to the ignition switch and run a dedicated wire to the batt for the voltage reference.

Excellent idea

wph351

iTrader: (3)

solved

All great ideas. Thanks guys. I finally found my problem.

I'm running a stock 4th gen f body underhood fuse/relay box. I pulled the box containing the ignition relay out of the mount and rolled it upside down. Started the engine to check voltages in,out and controlling the ignition relay. All seems fine. Decided to go for a ride and check it again. With the engine running I rolled the box right side up. As I did the ignition relay started chattering open and closed. The engine began sputtering and stalled. Ah Hah!
I was able to isolate the problem wire. 3rd gens have a heavy pink that supplies ignition 12v to basically everything in the engine bay that needs it. I used that wire as the hot side of the control circuit on the 4th gen ignition relay. When I removed the 4th gen fuse center from the donor car, I cut the wires about a foot down. The butt connector I used to connect the 3rd gen big pink to the hot side of the 4th gen ignition relay control.....had a bad crimp on one end.

I repaired the joint. SOLID 13.75 volts when hot under any driving circumstances, with anything on. My problem is now fixed. Thank god.

joecar

How did you repair the joint...?

wph351

iTrader: (3)

Cut out the connector, installed a new one.

00pooterSS

iTrader: (40)

If you're gonna butt connector it get one of those weather proof ones that heat shrink and seal.

Glad you found it, solder that beoch if you have a little torch.

wph351

iTrader: (3)

I used a generic butt connector as a stop gap measure. Once I cut the original one out, the wire was to short to solder. I'm going to solder in a length of wire when I install the meziere sitting on the bench that just arrived today courtesy a fellow ls1tech.com allum.

00pooterSS

iTrader: (40)

Sweeeeeetttt!!

89ROC-Z

iTrader: (11)

Wow... glad I'm not the only one with this problem.

I have a 3rd gen swapped, currently running a 145 amp alt that the local electric shop rebuilt for me. The plug is 4 prong but only one wire going to it.

At cold start, idling, I get 14+ volts. I gradually rev to 3500-4000 rpm and it drops to battery voltage ~12 and I lose fuel pressure/lights dim.

Is buying a kg3 alt off of LKQ really the only fix for this? I would think under minimal load (no lights on, etc) that the belt wouldn't slip at 3500 rpm. The belt is new and the tensioner is new as well.

wph351

iTrader: (3)

Have you had another alternator on the car? The kg3 isn't the only solution. My problem ended up being else where. What is the history of your attempts to fix it?

89ROC-Z

iTrader: (11)

When I first did the engine swap, the old truck alt didn't charge at all so I had a reman 145 put on.

This reman 145 looses voltage after 3500 rpm. Everything is grounded very well.

What did you do beside the alternator swap?

89ROC-Z

iTrader: (11)

I just picked up a 140k mile kg3 alternator to swap on tonight to see if that helps

wph351

iTrader: (3)

I did the "big 3" wire upgrade. I fried at least 2 reman alternators with high rpms. Just be very sure the associated infrastructure is good before pegging problems onto the alternator. I.E. Battery, battery terminals, trigger wire etc. etc.

89ROC-Z

iTrader: (11)

Is that just additional positive and ground wires? I have the engine grounded on 3 spots, and 2 grounds off the battery.

00pooterSS

iTrader: (40)

Sounds like you're okay there. The used truck alt isn't the only solution, but so far it's the only consistent option.