Electrical Issues
 

This is my first post on my ERA #491 that I built back in 1997. It has low miles. It has the 427 SO with 4 spd. I recently replaced the standard Delco battery I had in it for years with an Optima red top. I think my problem likely has been going on before that but I am not sure. I notice the ameter sits at zero at idle. It will swing positive when I punch the throttle and it will swing negative when I turn on the fans. When I turn on the headlights the engine cuts off! I checked the fuses and alternator belt and all the fittings that I could see. I replaced the voltage regulator but have not looked at the ballast resistor. It has the Mallory elec. ignition. Anybody have any ideas or know of a good auto electrician in the PeeDee area of South Carolina? Tom

Normal.

Normal.

Not unusual at all.

Well, it shouldn't do that. Does it kill the engine even if you're revving at 2000RPM when you turn the lights on? Or does it only kill the engine if the fans and the lights come on at idle? Has it always done this (since 1997)? It takes five minutes to pull an alternator off an FE -- instead of testing it yourself, I think you should just pull it out and take it down to your local Autozone, or whatever parts place you have in your area, that will bench test it for you. Most places do that for free. Disconnect your battery cables first since the clearance from the head to the connections on the back of the alternator are pretty close on an FE. Once you know your alternator is up to snuff, you can then work your way up stream. Whatever the problem turns out to be, I'm betting it will not be a big deal.

This may help.....



http://www.clubcobra.com/photopost/d...charge_sys.jpg

Then again....:LOL:

Holy Cow!
 

Gosh FWB! If I could figure that wiring out I wouldn't be posting. You want a free trip to Myrtle Beach - my treat - just fix the car! Thanks, really -I will study it and it might actually give me the answer. Meanwhile back at the ranch - I went out to the car and cranked it up to answer patrickt on his post. I cranked the car up and revved it up and hit the light switch - I saw the instrument lights come on and the headlights might have flashed on an instant and then it went dead and now will not crank so I think I fried the module in the distributor. The fans are automatic and were not on at the time. I had that happen a couple years ago - got a replacement somewhere in the garage so now I will have to redo that. I have always been a points guy never trusting electronic ignitions but that is what the engine builders for ERA put in the motor. Never had a bit of trouble with that engine otherwise.
I was thinking that if the ammeter went positive that the alternator must be okay but that is too simple. I will take it off and take it to the NAPA boys for a test. If it is OK then I will backtrack. One thing I have noticed over the years is that sometime the turn signal lights in the vehicle will intermettently not work as if they are underpowered - ditto the horn. Never gave it much thought figuring one battery was not enough. Thanks for the info guys. I will let you know as things develop. The car can be seen on the ERA photo gallery BTW. Tom

Ps
 

The photo on the ERA site is on p.2 just above the TWINS photo. It is the red one next door to the blue one. Tom

Tom, if doing that resulted in the car no longer cranking (meaning that when you turn the key you hear nothing, or at the most a little "click" from the starter solenoid, then the culprit was almost certainly a bad connection from a POS wire or corroded ground. The bad connection will be either at the battery posts themselves, at the starter solenoid, or at the block or head where your black ground wire leads to from the negative battery terminal. You must remove the wires and actually inspect them because the wires could be corroded and broken just inside the insulation and you won't really see it.

Follow Up
 

I realized later that if the module was shot then shouldn't it turn over but just not start. So I went back out to the garage and turned the key and nothing. So I turned on the fan blower ( the car has double fans - one big one on the radiator inside and 2 small ones on the front). The fans ran but nothing else. I turned the key again and it fired right up so it sounds like a ground or other loose wire as you say. I am still going to test the alternator in looking at the wiring. I had a 73 Corvette that had a bad ground. It came out of Chicago and I happened to bump the ground wire while under it and it sparked and I pulled on it and it came loose. It had corroded. Sold that car in 1991 and had to get another toy so decided the Cobra was a good thing (another story for later). Maybe I have a short in the wires to the battery when replacing with the Optima. I always tape the positive in place cause once you get that battery in place you dont want to mess with it.
One other thing. I don't remember with my car over the years but I was thinking the ammeter should read 12 -13 volts while idling to show that the battery is being charged - you sure it should be zero at idle? Tom

The ammeter doesn't measure volts, it measures the current that is travelling to, or from, the battery. Once the battery is charged, the alternator is providing all of the power that the car needs, so almost no current is headed through the ammeter to the battery -- so it shows zero. But when you turn the fans on, and the car is idling and the alternator is running slow, it is not unusual for the battery to "supplement" the power that the fans need and then you see a minus value on the ammeter. As you rev the engine up, the alternator makes more power and the the gauge swings back to zero or positive.

Your problem is almost certainly a bad connection or corroded wire -- the ground wire on the block/head is a likely culprit. It could also be the connections at the ammeter itself, but that's much less likely than the battery, starter solenoid, and block/head itself.

Bad Ground
 

vwvwvwvwvw

Thanks
 

Thanks guys. I really appreciate the input. I will check the main wires from the battery and the chassis ground. I will also look at the alternator. Take it off to clean and test. Tom

I am certainly not an electrical engineer. So I look for simple tests and simple solutions.

As I understand it, an ammeter measured current draw vs. available current. Very differant than a voltmeter. I would be curious to see what the volt are in each of those situations.

In any case, it sounds like there's too much draw, and not enough avalailable amps. you keep adding a load, until the system is maxed out. The engine dies because there isn't enough juice to run the ignition, and it it quits.

The battery should supply enough juice to make up the differance. For a while. You can run the engine on battery power alone. But if the battery doesn't have enough reserve, you're dead in the water.

After checking all your connections, I would have both alternater and battery load tested.

Ground
 

Hi,
Take the alt off and file or sandpaper the places where the bolts go through to hold it to the head, your BAD GROUND is there.
Perry.

The ERA wiring harness has a black wire that runs the ground to the alternator -- but it never hurts to check all the ALT connections (which he'll certainly do if he removes the alternator).

100 amp alt
 

Hi,
The alt puts out alot af amperage and needs a #8 pos and #8 grd wire. I find that more amperage is blocked by a high resistance grnd at the mounting bolts. Also with a chrome alt you need to grind or file the chrome off so there is a good ground at the mounting bolts.
The fans need a relay to isolate them from the alt and ignition or they can back feed a voltage spike and blow the ign. On MSD igition you need a relay on the main power or the engine can run on from backfed voltage from the alt or fans, NHRA tech will check that the engine does not run on.
Perry.

Thanks Again
 

Thanks for the extra advice Perry. Nice looking Daytona BTW. I think ERA scrapped their plans to build their version of the Daytona. To earlier posts it seems I am confusing ammeter and voltmeter. I guess a voltmeter would read 12 volts at idle and ammeter zero assuming nothing major drawing the current.
I am busy this week with work so it will be this weekend before I can get to the car. Gotta work to pay for these toys! Tom

Unplug both headlights. Try to replicate the problem. If nothing, plug in one headlight, repeat test, if nothing, unplug the 1st headlight and plug in the second, test again...now you have some idea of where to start looking..

Tom, when the car is not running you will see about 12.6 volts on your volt-ohm meter (VOM). When the car is running you should see 1.5-2.0 volts higher, say around 14.3 volts, or the like -- but not 15 volts, that's too high.

I, too, thought that the M in VOM was meter, until someone explained that it was actually "Volt-Ohm-Milliampere..."


But it took years for me to remember it:rolleyes:! Now with the digital meters available it's easier to remember DMM for digital multi-meter...

You're (we're) showing our age here Patrick:cool:.

Follow Up
 

Well I finally got off my duff and got my hands dirty with this. I took the alternator off last night and took it into NAPA for a test. Kelly the guy that works there is an old friend (he is into Model A Fords BTW). The alternator tested bad. I could not believe it. It looked in mint shape. So I bought a rebuilt one and kept my core. $40 bucks. What a great price. Put it on and of course it seems to be working fine. I checked continuity of the wires to the alternator and they were fine. I dug into the horns as there seemed to be an intermittent loss of horn and found a bad ground at the harness at the driver front. It is at the left horn harness. Actually I should have filed off some of the powdercoat there when I put it together 15 years ago. I also found that one of the horns doesn't work and probably never did. I tried a direct wire to it and never could get it to sound. I did not mess with the tuning screw which looked like it was in proper place. Replace the horn some day. Now the lights. I checked fuses - OK. I noticed I could get the instrument lights to work some of the time but not the headlites. I noticed the reostat for instrument lights and turned it a couple times and the instrument lights would come on and off so I think the reostat has some minor corrosion internally. I worked it some and finally all the lights would come on. It is cheap but period correct. It probably needs to be used a little more. Plus Marion SC is in a swamp - Swamp Fox City is our motto so damp is ever present - another excuse to get out and drive. I cranked it up and it cranked fine. It idles a little rough like a plug or wire is off so I will check that. Who knows how long I have been running on battery? I have never tuned the car - do you tune an electronic ignition? I know how to tune a points ignition but not this newer stuff. I will figure it out. Maybe advance or retard the spark some till it sounds right. I have a nice SUN timing light. I did replace the plug wires with some from NAPA. They are 7mm and should be 9mm so they gotta go. Maybe put them on the boat. They don't even fit in the looms. Thanks for the help fellas. Seems everyone had something to offer on this. Tom