Pegged amp gauge

[lasvegas69charg]

Hi. I was driving the other night and noticed the amp gauged pegged to the right. First thing I did I was come home and did a search here on the forums. I have checked everything out per the searches that I found. Voltage battery is 12.6. When the car is running the battery voltage is 13.9. When I disconnect the voltage reg the gauge goes back to 0. I changed out the voltage reg with a new one and still same issue. All the wiring is new in the car and have never had this problem before. I have a power master 7509 90amp alternator in the car that i bought new about 1.5 years ago. There is also a really bad electrical burning smell coming from the alternator and when I have the wire connected to the voltage reg there is a slight whine coming from the alt but goes away if I disconnect the wire on the voltage reg. The car is still wired as factory setup. I'm guessing the alt is bad. Any suggestions?

[b5blue]

Sounds like the regulator has puked. (Runaway charge.) Check bulkhead connectors also. (They burn quickly.)

[lasvegas69charg]

I replaced it with a new voltage reg and stills pegged. All the wires and connectors look new.

[Pete in NH]

Hi,

How old is the battery? I'm wondering if you have a shorted cell in the battery. If you have another battery you can swap in, I think it would be worth a try. From your voltage measurements it would seem the alternator and regulator are trying to do their job correctly. It just seems the alternator is trying to supply a lot of current.

[lasvegas69charg]

Hi Pete. The battery is a 1.5 years old. It's a optima red top battery.

[b5blue]

A short would do the same. 

[lasvegas69charg]

If there was a short would a fuse blow?

[b5blue]

Not if it's in front of the fuse.    Isolate the main feed from the alt and check for continuity to ground. If a wire got hot and melted inside a bundle it could cross to another circuit. (You reported a stink smell.)  Do have the battery checked, I'd remove the alt and have it bench checked also.  This will be a process of elimination.

[lasvegas69charg]

Battery checked out good. I checked the alt for grounding issues and I disconnect the bulkhead connectors and went thru the connectors for grounded terminals. Didn't come up with anything. My last resort is the alt. I have the powermaster 7509 using the stock voltage reg. I was thinking about going to 7409 one wire. After reading powermaster website all you have to do is connect a wire from alt to battery. By doing this will my amp gauge still work in the car? Will there be any other wiring needed to be done?

[Ghoste]

Doesn't solve your problem but I thought I'd add that if you are running a higher output alternator on the car you might want to consider bypassing the ammeter and some other wiring upgrades.

[b5blue]

We never covered what regulator you have or even year/mods to car.  I see a 69 in your pic. is that it? 69 different from 70 up reg. and mods to stock ignition?
   I have no info for one wire alts for you. If it ran good for 1.5 years I'd be inclined to find/fix as is but know nothing about Powermaster.

[lasvegas69charg]

its a 69 with msd ready to run ign, powermaster 90 amp alternator with stock electronic voltage reg with msd atomic fuel injection.  Otherwise all wiring is new and stock going into bulkhead and under dash.

[b5blue]

its a 69 with msd ready to run ign, powermaster 90 amp alternator with stock electronic voltage reg with msd atomic fuel injection.  Otherwise all wiring is new and stock going into bulkhead and under dash.

"Stock electronic voltage reg." is a one field wire for 69? (My car is 70, 2 field, solid state reg.) I've seen posts of 68-69 type solid state regulators not calibrated correctly yet they function. I think in Hot Rod mag. fixing car write ups. (?) 

[lasvegas69charg]

yes its a one wire field alt and voltage reg.

[b5blue]

Lets hope Pete chimes in on single field testing.  Something is triggering full output.

[lasvegas69charg]

pete? nacho?

[Pete in NH]

I looked up a Powermaster 7509 alternator and the description calls it a 90 Amp, two field wire alternator. A two wire fields alternator is meant to be used on a 1970 on up Mopar with the electronic regulator system. A 1969 used a single wire field alternator with an electromechanical regulator.  Many of these older electromechanical regulators have been replaced with an electronic replacement type that is not the same as the 1970 and up Chrysler electronic type. These 1969 and earlier electronic replacements are all after market units and many are of Chinese origin and on questionable quality.

To use that Powermaster 7509 you would need to ground one of the alternator field terminals and connect the green wire from the regulator to the other field terminal. A 1969 type stock regulator will have one blue wire going into a push on spade type terminal and a green wire on a separate terminal to the alternator. Is that what you have on your car?

Also, make sure the regulator mounting is well grounded. Old, half stripped out, rusty sheet metal screws do not make for good grounds.

A picture of the regulator and back of the alternator would sure be helpful at this point.

[b5blue]

Pete I'm glad your here! 

[lasvegas69charg]

I have the alt set us a single field. I originally did that when I did the install. I have a good solid ground on the voltage reg using a star washer behind the voltage reg.

Here is what I found out today because since this has happen the only change I did was installed a different fuel pump for my fuel injection.

If I keep everything like it is and I start the car the amp gauge goes to +40.
If I connect the fuel pump to a separate stand alone 12v battery and start the car the amp gauge goes to +20 then very slowly starts dropping due to charging the battery.

My car is wired with new wire harness and it's stock. I haven't did any parallel wiring as nacho has describe in other post. Could the fuel pump be drawing this much current to cause this? I know my power wire coming from my msd atomic computer is the same gauge as the wire going from the alt to the bulkhead. My msd atomic computer is wired directly to the battery. I am no electrician guru but would connecting a 8 gauge wire from alt to battery be the fix?

[b5blue]

Crap now you tell us..... You must be feeding the pump from battery so the regulator sees low battery and is pumping through the ALT gauge to top up the battery. Mopar feeds everything off Alt. output, the battery just starts the car.  You can add a 40amp relay to feed the pump that is activated by ignition switch.  Tap alt. output to supply power. 

[lasvegas69charg]

Msd instruction say to connect to battery. What your saying is I should actually take that to the output of the alt instead?  I believe the new fuel pump draws more current than the old fuel pump but I didn't think nothing of it. I thought a fuel pump was a fuel pump. Should I also place my car amp to the alt output also or keep it to the battery? Sorry for leaving that part out.  

[b5blue]

Well if you want to retain all that new harness and the "way" the factory figured it out yes. GM's of the same vintage all draw everything from the battery, they were designed that way. What you have I can't speak with any authority on as I've no experience with MSD injection or otherwise and no Power Master Alt. to boot. I do know if your wiring is stock... whatever draws off the battery will be replaced from Alt. output into the harness, through the bulkhead, past the main splice that feeds the fuses, into-through-out of the ALT gauge back through the bulkhead to the starter relay main feed and finally back to the battery. How your running a 2 field Alt with one wire I don't know, I think one field should be grounded? Again I don't know for certain. (My Denso matched 70 Charger wiring closely.) The part about the gauge reading 20 and returning to center is correct it should and did read that way. If drawing anything off the battery it would read off the left side of the gauge. (So things were working and seemed okay whatever you had going on!) 

[lasvegas69charg]

Thank you Neal for helping me fix my problem. I have the 2nd field grounded. It came with instructions if the car was a 1 field.
There was one thing in the post that I'm confused. You said the gauge should be to the left if draining from the battery. With the way I have the msd efi connected to the battery my gauge is to the far right +40.
Also is there any other ways of wiring it besides going straight to the alt output or would say that will the best route for both my msd efi and car amp?
Thank you again.   I was about ready to buy a new alternator.

[Pete in NH]

If you think of the ammeter as an indicator of whether current is going into or out of the battery it helps you understand how this system works. The Chrysler designers intended the ammeter to do just that, tell you whether the battery was charging or discharging. When you add things like amplifiers and fuel pumps connected to the battery, the ammeter thinks the load current is battery charging current and the needle swings to the right.

You have to remember that in these 40+ year-old cars electrical system demands were relatively small. Fuel pumps were mechanical and sound systems were 2 watt AM radios. The designers never thought about electric fuel pumps or big sound systems. In these cars the wiring size, ammeter and bulk head connector pins limit how much current you can move around safely. The original alternators were 45 amps max. and that is what the system can handle.

If I were going to try to add things, as Neal said, they need to go on the alternator output to keep the ammeter working correctly. But, it really goes further than this. because the system wiring is going to struggle with the new 90 amp alternator and loads put on it by the new accessories. How big is your new sound system? If you are trying to run a big sound system , it may be time to think about some re-wiring and bypassing the ammeter and going to a voltmeter. And as Neal suggested the fuel pump should be controlled by a relay and provided with its own fuse.

[lasvegas69charg]

     Hi Peter. Thank you for the info. I understand it now. I just have 2 small alpine car amps. One amp pulls 10 amps and the other pulls 15 amps. With the stereo on the only time the amp gauge moves to the right is when there is alot of bass in the music.
    I just got done wiring the amp main power supply 6ga wire and the msd computer 12ga wire to the alternator output post. The msd computer is internally protected and has a built-in relay to power the fuel pump which doesn't require a fuse or relay. I haven't started the car up yet to test it because I am also doing a few other things to her.
    Since its really hot here in Vegas, I usually run the AC most of the time.  Would it be a good idea to put a relay on the fan blower motor   OR   run a 10ga parallel wire from alt output post to the charge side(right side) of the ammeter   OR    run a 10ga wire from alt output post to starter relay battery post?