'78 - Electrical Problem?

[sethmerica]

Hi everyone! Great site, I hope someone can help with my problem.
Here goes.... I recently got my '78 25th Anniversary out of the shop. I had it completely repainted in a candy apple apple blue (looks awesome ), also had some engine work done at the corvette shop next door. They replaced the cap, rotor and distributor. Also replaced the alternator...and some various hoses and wiring. After everything was paid for I got in my car and was all ready to drive away but the car wouldn't start. Nothing happened when I turned the key. They guys at the shop said that the battery was probably drained due to the doors being removed while it was painted. After a jump start it seemed to run fine. I drove about 15 miles down the highway...everything was fine... when I got off the highway, as I slowed down, the car began to feel weak...then died. I attempted to restart it, it tried to turn over but no spark, I tried again and nothing happened. After embarrassingly pushing my car in to a parking lot I decided to buy a new battery. I thought maybe the battery had been so drained thet I needed a new one. After the new batery was installed it seemed to drive fine. I drove home (about another 20 miles away) with no problems. The next morning I drove up to Sacramento from my house in Napa (about 60- 70 miles) and had no problems. On the way back home, I was about half way, I pulled off the highway for some gas and once again- as I slowed down I could feel my car weakening and then- dead. I tried to restart it and after one try (it was trying to turn over but no spark) nothing would happen. I then had my car towed home- I thought maybe it was a bad alternator so I removed it and had it tested at the local Kragen but it was fine. Now I am stumped as where to look. Oh yeah- to add insult to injury- this morning I went out to try to start it... it started just fine. My battery guage also read full charge (but when I turned on the headlights I could see a slow drain). I'm afraid to drive it back to the Corvette shop because I don't want to get stranded again.
Please help- ad :confused

 

[78SilvAnniv]

Welcome sethmerica!

Welcome to Corvette Action Center.

You've checked all the things I would have checked. One thing I could mention is a starter heat soak problem...that may explain the no-start when the engine is hot, but it still doesn't explain the loss of power and dying when coasting or slowing from hwy speeds.
I wonder if it could be a fuel delivery problem? Fuel boiling away when the fuel delivery rate slows...
Heidi

ps...I'd like to see pics of a Candy Blue '78!

 

[cesully]

It could be a wiring "short" somewhere that is draining the battery. This could be part of the alternator wiring since the alt. charges the battery when the motor is running. A lot was done recently to your car that could have caused a hot wire to be shorted to the frame (ground) causing a dead battery.

If you have one of those portable battery booster/chargers (good investment if to don't) take that with you and get the car to the shop that did the work. Shorts can be a bugger but a good machanic with electrical experience should be able to troubleshoot and fix.

Let us know what it was when you get it fixed. This can happen to any of us so it is a good thing to pass on.

Oh and the pics?

Good luck

Sully

 

[cesully]

I read your problem over again and I would recommend to check the alternator drive belt, make sure it is tight with about a 1/4 deflection measured at the middle of the belt between alternator and engine pulley.

This can be check immediately and resolved yourself if it is the culprit.

Sully

 

[Culprit]

Welcome to CAC!

Does your car have underdrive pulleys? If so, they might not be spinning the alternator at enough RPM to generate electricity when you're in stop and go driving/parking lots and such (ie, when you got off the highway and slowed down).

Also - you said you tested the alternator - but did the shop install the proper alternator when they replaced it. If they put in the wrong alternator, that could have the same effect as if you did have underdrive pulleys.

Hope you get it sorted out quickly and easily. And I'm with Heidi - post some picts for us when you get a chance.

Semper Fidelis,
Culprit

 

[titan81]

hi there and welcome

i had this problem on my camaro
it was the solenoid on the starter.
There was no heat shield so on fairly cold starts it was fine
but it would sometimes die or not restart. I put a new starter and heatsheild
on it was fine that was 5 yrs ago.
Other than that your alternator would be the next issue

 

[curtis]

Sounds to me more like bad ground connections, probably the one from the frame to the block. Also I would check the alt output while it is in the car. Check battery voltage with engine off. Start car and check battery voltage again. If it is higher, then alt is working. If voltage is lower when running, then alt is not putting out enough, which could be too much load or bad grounds. :J Well this sure is a goofy smiley!!!!!!?????

 

[sethmerica]

Thanks

Thank you everybody, for all of your help. Sorry for no pics yet, I will have some up tomorow. Also, I have just started working night shift (I'm a firefighter and now working night dispatch) so I'm trying to adjust to the hours, and work on my car... and spend time with my wife (I think she gets jelouse when I wake up and immediately walk out to the Vette...oops).
Anyways, today I removed and cleaned as many ground wires as I could- alot of them were very caked in grease and buildup. I also checked the alternator belt tension and it was at 1/4 inch as it should be. After doing these, and a few other small tweaks, I took it for a drive around the block. It did fine so I decided to drive it downtown. It also did fine on the longer trip. I was only driving for about fifteen minutes though so I'm not sure if it was enough time to "trigger" the problem.
I am curious about the "starter heat soak problem" that Heidi mentioned. Basically I'm not sure what that is- are you saying that the starter may be overheating? How about the fuel delivery theory- where is a good place to start for that?

Thanks again, I will post alot earlier tomorow and let everyone know how it's going. I'll post those pics too.
-Seth

 

[P-38F]

To check your charging sys. all you need is a volt meter and a fully charged battery.Put the meter across the bat.terminals while the eng. is running,you should read above bat. voltage (12.5 volts) something of 13-14volts with all accesories off. then turn all acc. on (a/c blower high,lights and wipers),again voltage shouldread above bat.v.This is to see if the alt. can keep up with the demand.If you read only bat. volt. the alt.is probably at fault,but before you condem the alt.,check the wiring at the (plastic connector plug) back of the alt. with ign. sw.on engine off,should be 12v.and check circut from alt. to bat.(large terminal back of alt) The biggest killers for alt. is heat and the electronic voltage reg is most likely at fault(internal part of alt.since1973) The car is the best test bed for checking your alt.your wasting effort if you remove it and take it down to have it bench checked.
Heat soaked starter is the starter fails to work because the plunger inside the soleniod has over expanded and frozen into place until the motor has cooled down enough and sufficiant clearance is restored then it will work again. If all is the same and( no past history of this problem) nothing was changed this shouldn't be the(a) problem.

 

[sethmerica]

Well I'm going to risk it and drive my car to the shop. First I will buy a portable charger though. P-38F, I did a charging system check using my battery guage inside the car. Will this give me a basic idea or do I need to buy a volt meter? When I did the test using the bat. guage here is what happened. After the car was started it read about 14 volts. As I turned on more and more accesories, eg: stereo, lights, A/C..., the volts dropped to about 12.5 or even 12. The needle on the guage continued to slowly drop giving the appearance that yes, my alternator was not keeping up with the demand. As soon as I started turning off accesories the guage read a higher reading...I also noticed that after I turned the lights and stereo off the A/C was running more powerfully.

One thing that I did not mention earlier but I think I may have found the answer for, thanks to P-38F, is the selonoid problem. This doesn't always happen but sometimes after I've been driving for some distance if I stop to get gas (or just turn the car off) I'll have to wait 15 minutes until it will start again. When I turn the key nothing will happen...untill 15 or so minutes. I would say that I definately need a heat shield for my selonoid. Thanks P-38F.

I couldn't find my USB cable for my digital camera (just moved so it's probably still packed away somewhere). So I pulled up a couple pictures of my car befor it was painted- it looks a hundred times better now. I have also removed the bra.
Hope these post right-:cool

 

[curtis]

Now it sounds like you could use an alternator that puts out more amps at idle than the stock unit. Heat soak solved on my 76 with the insulating blanket thing. About $20. good luck!

 

[P-38F]

The voltmeter in the car or any of the instuments are not very accurate,lets just say the are good references and are better than any idiot light,since you know your car you know where normal indication is generally,anything else can indicate an up coming problem. I suggest buying a voltmeter for accurate troubleshooting.

Sometimes even though the parts you buy from the parts store are rebuilt or brand new, they may be defective, and if you are not sure of your troubleshooting knowledge just makes the problem worse or more difficult.I wouldn't be surprised if some rebuilders just repaint them and put them back on the shelf.I have had many various parts that were bad from stock, You may just have gotten a bum alternator.

 

[sethmerica]

Well I drove down to Kragen yesterday. I had them test my Alt. with a voltmeter while it was still in the car. It read good. I also bought one of those portable batery chargers- even if I don't need it for this problem I think they are definately a good buy. On the way home (about 5 miles away) my car died again!!! I called the Corvette shop that had origionally worked on the car. I told them that I was still attempting to get back so they could help with the problem but that I was, once again, sitting on the side of the road- getting compliments from passerbyers on having such a nice car- but none-the-less, broken down on the side of the road. Mike (from the shop) reminded me that the paint shop had misplaced my crome gas cap- he said maybe the plastic temporary gas cap was not breathing so maybe I should remove it. I removed the gas cap- attempted a restart...and after some sluggish strugling she started! I drove around the block expecting a breakdown but my car kept driving. I decided that even if it was only going to last for a little while it was working so I was going to drive. I took the T-tops off and headed for the Vette shop. I swear I thought that the gas cap was the problem and everything was fixed...untill I got to within about two blocks from the shop. Once again my car suddenly felt weak and died. But this time it wouldn't even try to turn over. I think the not turning over problem is the heat soak / starter-selonoid and the car dying is something else, I'm thinking maybe fuel related now. ...who knows:L :cry .

My car is now back at the shop and I am stuck driving my SUV again. Once again, when I find out what the problem is I'll let you all know.

 

[curtis]

If it is not voltage shutting you down, maybe you have a fuel line too close to high heat source and you get vapor lock.