Electrical help needed

[2500HD]

I replaced all of the A/C ducts on Sunday and had the doors open for most of the day. When i finished the truck was slow to start but finally kicked off and ran and idled great. the rest of the day it was slower than normal but started each time. it started this morning and i made a stop before work and it would not start. jumped it off and it would not start later in the day. i drove to my over priced local battery guy and with the truck off and a load on the battery i had less than 10 volts so a new battery was put in and it started and idled higher than normal and very rough. While running it showed 12.4 volts so i bought and installed a voltage requlator. still idled high and rough. set the timing to 8 degrees without much change. While changing the regulator i found a green wire that was capped off coming out of the harness that supplies the regulator. I do not have a volt meter at home so will have to check the current volts latter.

Before changing the battery it idled between 650 and 700 and smooth as butter. It now idles at 850 or 900 and like a plug wire if off.

Anyone have any ideas?

[2500HD]

ttt. Anyone?

[BIG69GMC]

did you mess with anything electrical that day??? if you did i would go back and double check it. its obviously somthing you did that day. maybe your pinching a wire now that you messed with the ducts?

[Andy4639]

Have you got all the vacuum hoses hooked up correctly? The vacume can cause all kinds of rough idle issues.
Automatic transmission should be around 600 or 700 I think at idle in park.

[2500HD]

Originally Posted by BIG69GMC

did you mess with anything electrical that day??? if you did i would go back and double check it. its obviously somthing you did that day. maybe your pinching a wire now that you messed with the ducts?

Nothing electrical. After i finished the ducts it started slow because the interior lights were on most of the day. After it started it ran and idled as normal. I was affraid of moving wires around so i was very carefull and was pleased that all guages and lights still worked after the duct install.

[2500HD]

Originally Posted by Andy4639

Have you got all the vacuum hoses hooked up correctly? The vacume can cause all kinds of rough idle issues.
Automatic transmission should be around 600 or 700 I think at idle in park.

All vacuum lines are hooked up correctly. I replaced all of them one at a time the day before. Again after i was done start and idle where normal. It was idleing at 650 to 700 before the battery problem.

[BIG69GMC]

thats weird, have you double check all of your vacuum hoses at your ac ducts? maybe you missed one or did you replace all of them? maybe one came off? i would double check each and everyone of them.

[red71cheyenne]

Do you have regular points still or HEI? The battery dying may have killed your module in the HEI if you have it. Can't say I've ever had a problem like this and if your vacuum lines are good, thats about all I can think of.

[Longhorn Man]

it sounds like another fault showed up at the same time your battery died.
Also, if your only showing 12 volts when running, then you aren't charging either

[2500HD]

Originally Posted by red71cheyenne

Do you have regular points still or HEI? The battery dying may have killed your module in the HEI if you have it. Can't say I've ever had a problem like this and if your vacuum lines are good, thats about all I can think of.

I guess i could have given all the details

I installed a pertronix, cap, rotor, coil, plugs, plug wires and new vacuum advance all at the smae time. Set the timing and was idling smooth at 650 or so.

three or four days latter i replaced all of the vacuum lines one at a time. Advanced the timing to 10 degrees and idling was smooth at 650 or so.

three or 4 days later is when i replaced the ducts and developed this problem.

[2500HD]

Originally Posted by Longhorn Man

it sounds like another fault showed up at the same time your battery died.
Also, if your only showing 12 volts when running, then you aren't charging either

I would agree. Is there something under the dash that would cause the high and rough idle? Maybe a vacuum line from the A/C controller?

Rodger that.... i have not check the voltage after I installed the new regulator. I will do that today a probably install a reman alt from NAPA just to close the loop.

[Longhorn Man]

I highly recomend NOT getting a reman'd unit from NAPA. Shops have known to avoid them for years. I would sooner go to a junk yard or get your old one rebuilt. They are all made in china now, and thats a bad thing. Quality is down the crapper. NAPA is where i generally tell ppl to get stuff, but not this.

[a.c.1]

In all my trials with electrical work, I've learned one important lesson. Bad grounds make funny things happen. I always check, clean and tighten all cables including positive and ground cables at the starter before i start spending money.

[mr48chev]

Originally Posted by a.c.1

In all my trials with electrical work, I've learned one important lesson. Bad grounds make funny things happen. I always check, clean and tighten all cables including positive and ground cables at the starter before i start spending money.

Wise words there and something that you really need to check before spending any more money.

Check the alternator out and see if it is working right or capable of working right before changing it out.

Is the plug going to the regulator hooked up and is it hooked up correctly?
Is there a specific reason you changed the regulator?

About the only thing that normally goes wrong with the external regulator alternators is that the brushes wear out and don't make good contact with the rings on the rotor. If you short something out on the truck you might blow a diode. Also once in a while a stator will fail but I think that is primarily due to over charging. And the bearings will make noise after a while but they are easy to change too.

[2500HD]

Originally Posted by a.c.1

In all my trials with electrical work, I've learned one important lesson. Bad grounds make funny things happen. I always check, clean and tighten all cables including positive and ground cables at the starter before i start spending money.

I had the same thought yesterday. I was checking the ground on the water pump and the eyelet broke off. I thought i had found the problem but after a new ground cable and a new positive end the problem still exists.

i have almost rubbed a bald spot scratching my head.

[2500HD]

Originally Posted by mr48chev

Wise words there and something that you really need to check before spending any more money.

Check the alternator out and see if it is working right or capable of working right before changing it out.

Is the plug going to the regulator hooked up and is it hooked up correctly?
Is there a specific reason you changed the regulator?

About the only thing that normally goes wrong with the external regulator alternators is that the brushes wear out and don't make good contact with the rings on the rotor. If you short something out on the truck you might blow a diode. Also once in a while a stator will fail but I think that is primarily due to over charging. And the bearings will make noise after a while but they are easy to change too.

I put the plug going to the regulator in just like I removed it. It will actually only go in one way. I changed the regulator because the alternator rebuild shop suggested I do that first and that he really thought that was the problem even after i pointed out that the regulator looked newish. I am going to have my alternator rebuilt I guess.

[dirtball]

I would check the condition of the vacuum canisters you just hooked up. One could be torn or leaking. If you disconnect and plug the whole loop for the A/C you could tell if there is a vac. leak in one of the pods. Any chance while the voltage was down you fouled out a spark plug?

[Andy4639]

The alternator doesn't make the truck run rough. It was showing 12.4 at idle right. What did it show when you speed it up? Hold the throttle at about 2 grand and see what it reads. 12.4 at idle ant that bad of voltage. The alternator has to get spinning good before it kicks in and puts out. The alternator doesn't make a idle bad or good. Take a voltmeter and put on the battery and rev it up around 2 grand and see what it tells you.
Bad idle is a vacum leak or distributor problem on the older motors. Grounds can make things happen to.

[2500HD]

Originally Posted by Andy4639

The alternator doesn't make the truck run rough. It was showing 12.4 at idle right. What did it show when you speed it up? Hold the throttle at about 2 grand and see what it reads. 12.4 at idle ant that bad of voltage. The alternator has to get spinning good before it kicks in and puts out. The alternator doesn't make a idle bad or good. Take a voltmeter and put on the battery and rev it up around 2 grand and see what it tells you.
Bad idle is a vacum leak or distributor problem on the older motors. Grounds can make things happen to.

I am starting to wonder if i hooked up the Pertronix correctly. I ran 12 volt from the IGN on the fuse box to the ignitor and to the new factory replacement coil. Should i have left the resistor wire in place so the coil would only receive araound 9 to 10 volts while running? Would the coil cause my problem after continued 12 volt use?

I did not rev the engine while checking the voltage. I thought i should have 14 to 15 volts while at idle.

[trusty72]

just some info to help out, a fully charged battery after leveling out has 12.6 volts. when running the alt should put out 13.4 - 14.3. u can eliminate this out of the equation. by the way put a one wire alt on it and forget it.

[Longhorn Man]

one wires are inferior to a 3 wire internally regulated unit

[trusty72]

oh ya and 12.3 is half half discharged and 12.0 is dead. this is not running no load of coarse.

[trusty72]

That sounds a lot like an opinion to me. I run natural gas compressors 24/7 365 days a year all with delco alternators some 3 wire and some 1 wire. guess which one get changed out more often? 3 wire hands down.

[Andy4639]

For a GM factory HEI distributor you want to take the resistor wire out of the picture totally. It needs 12 volts all the time. I'm not fimaliar with your setup to say one way or the other.
You can check the voltage at about 2 grand it should be around 13-14 volts.

[2500HD]

Got everything worked out.
1. installed new Flame Thrower coil -- did not fix anything
2. installed new Ignitor -- Smoothed out at higer RPM. Still idled like a dragster.
3. Found bad positive wire to the alternator -- did not fix the idle but corrected the charging problem.
4. I noticed a three port vacuum source that had one open port. I thought i recalled a plug on it but it was missing. I also noticed a empty port on the A/C canister so i ran a line from the empty port to the canister. This was the idleing problem. i removed the line i installed and capped it. Idles smooth as butter again. I must have knocked the plug off while removing and installing the distributor.

I think a number of problems came up at the same time.

Next in line is to figure out what is going on with the vacuum canister and why the PO has the heater core by passed. I smell a problem here.

Thanks for the help.