The Stovebolt Site Forums The Shop Area The Electrical Bay Frustrated!!

Can't figure out what the heck is wrong with my truck. Prior to relocating to the East Coast, I was having issues with it seeming down as though it were starving for fuel. Thought it was the TPI system and I got tired of it and switched back to a carb. Still had the same issues, switched back to the TPI and the truck sat for several months during my relocation. Recently took it out for a drive and still having the same issues. When it dies, it's as though the alternator (new) is not charging. I had the alternator tested last night and it checked out fine so I was wondering if perhaps is wired wrong. I have the main wire from the battery hooked to the stud, of the three wires from the pig tail, the red is also hooked to the stud, brown to the guage & black capped. Is this correct? Any other thoughts as to what the issue may be???

Hy mobileortho, could you tell us which alternator you are using and what truck it is in. All the internal regulator alternators I have installed only have two wires in their plugs. If your truck has an ammeter then the output wire (stud) must go to it and then to the battery in order for it to read correctly, more info is needed in order to help you figure it out.

does it have an electronic module

3B,I swapped the TPI & serpentine brackets from a 89-91 Camaro onto a 327 in my 1950 3600. I had to us an alternator from the camaro as well because of the brackets snd there are three wires coming from the pig tail, red, brown & black.

Joker, there's no module.

I dont see how the Alt would have anything to do with as you say seeming down.......but I am no mechanic by a long shot

I would check battery and make sure it is ok, and check all connections...

Battery checks out fine too.

If you charge the battery for a while, does the truck run okay for a bit then start being sluggish?

Have you checked battery voltage with the engine running? Should be around 13.5 volts to 14.5 volts.

did you just check it with a volt meter.. it can show 12 plus and still have a dead cell

...is the ground/positive cables switched on the battery.

(once had a 63 Impala that my friend borrowed the battery out of. I came home on the weekend and couldn't figure out why the car would not "get up and go". At first it'd start off like a raped ape then "die". Tried a bunch of things, talked to lots of folks.....Then I dropped by the radio shop, picked up my radio and installed it right there in the parking lot. When it wouldn't work I got the radio tech out to the car. He did some checking and told me my battery was hooked up backwards!!
I told him he was crazy..then I raised the hood. Oops, it was backwards and when I switched them the car again ran super.
Believe it or not......I was there!!

Alvin, when I hook her up backwards she spits at me. I'm speaking of the battery.
I wonder if your grounds are well connected Robert.

Got a chance to briefly look at it. I started with the alternator, someone suggested that it was wired wrong. It has three wires coming from the pigtail, red-jumped to the stud, brown-ignition/volt guage, & black which I assumed was ground, but someone told me that should be connected to the stud as well. Tried that hoping that would work but it still didn't so back to the drawing board. Going to get a voltmeter as many has suggested to check things out.

A guy at the parts store also suggested I was testing it the wrong way. My father taught me years ago to disconnect the battery cable while the engine was running to test the alternator, if it still runs it's good but this guy says that was true for older carbed motors but since I'm running TPI, it doesn't work because disconnecting the cable doesn't provide enough juice for the computer. Anybody else heard of this?

Hy mobileortho, you should never disconnect the battery while the engine is running, this could cause voltage spikes in the electrical system which some components cannot tolerate!

Hy mobileortho, it took me a while to find a wiring diagram on a 1990 Camaro, but from what I found the red wire could be looped back to the output post and the black wire as well, the brown wire should go to an ignition source (powered when the key is on). You mentioned going back and forth with fuel injection/carb, what are you using for a fuel pump? Seeing as how the problem existed with both carb and fuel injection could your fuel delivery system be plugged up in some way?

3B, the fuel delivery system checks out fine. The lines, inline pump, tank & filter are new. Imay be on to something though. Someone on another site said the wire to the alternator should be hot with the power off..... it's not.

Hy mobileortho, yes the wire on the output stud should be hot all the time, did you wire the alternator output through the trucks ammeter?

Think I found my problem!! The alternator wire had shorted out at the starter. A quick splice and power's restored. Hope to road test this later in the week.

The picture shows a broken wire. That is called an open circuit. A short circuit is when a hot wire goes to ground. Had that wire been grounded it would show a lot more damage than that.

You can test your alternator easily with the battery hooked up, you never need to unhook it while running.