alternator not charging enough?

Hi y'all. I got some more work done on the rail today so I'm too tired to go messing with it any more right now, but I have a question or two. (today I got the fire extinguisher mounted and used a ravioli can to help... also put a "cover" on my coil... and wrapped the rear axles in some padding for extra protection...and was lucky enough to have the high-pressure oil line that feeds the oil pressure gauge basically shatter in my hands... very brittle... so I replaced the entire line... lucky it happened at home in the garage instead of on the trails). Anyway... the other day I was driving home on the highway, doing about 70 mph or so. I turned on the regular running lights and also had the two big overhead lights on just for the heck of it. I'd only been driving with all of the lights on for about two minutes or so when I started to feel the engine start to lose power. It was like it was starting to miss... and it even did a couple of very small backfires... and with each backfire I slowed down a little bit. I suspected that my electrical system might be getting drained faster than recharged so I immediately shut off all of the lights. Instantly power increased and I drove home with no apparent troubles. Today after working on the rail some, I started it up to test the oil pressure gauge. I noticed that when I turned the key to the "start" position and the engine was turning over that it just would not seem to "catch" or "fire." The instant I would release the key so it would return to the "on" position, the engine would fire a couple of times before dying. I just did this a couple of times and then pumped the gas once and it started up. Seemed like while the starter was drawing on the electrical system to turn the engine over that it wasn't leaving enough for a good spark to get things started. That would explain why when I released the key and the starter quit pulling but the engine was still spinning some, that suddenly it would start to fire. The battery is almost new, I'm pretty sure... I looked at Speedy Jim's website and saw the procedure for how to test a generator. I guess even for an alternator the first step would be to measure across the battery terminals and then start the engine and watch to see what kind of voltage I get and hope for 14 volts or so. I guess I'll do that and also take a look at the condition of the spark plugs. I'm thinking I might want to go with some sort of high-output alternator since I'm going to be using a winch and I'm not sure how well a stock alternator would deal with that. Anyone want to throw out some suggestions of other stuff to look at or tell me I'm way off base or just share a funny joke you heard recently? Thanks!

"Stupid people are funny." - me

Reply to
Shag
Loading thread data ...

Sometimes a bad ignition sw will act like that.

Yes, see if the battery is getting around 14V (13.5 to 14.5) EVEN with all those lights on. If it IS, the Alt is OK.

Also, put the meter on the Coil wire and see what the voltage does with all the lights on.

Do the same test when turning the key to START.

If the rail was based on early wiring, the Headlight sw was often a problem area.

Make some tests and let us know.

Speedy Jim

formatting link

Reply to
Speedy Jim

It sounds to me like the extra current draw for your lights may have damaged the contacts in your ignition switch. I would suggest that you replace the switch, and then add a relay so that the extra light current doesn't go thru your new switch.

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

Reply to
Jim Adney

I barely made it home today in the rail... Had to stop 3-4 times and let it sit just a couple of minutes before it would run ok again. I was leaning towards this being some garbage in the fuel system somewhere, but just now went out in the garage and measured a healthy

12.4 volts across the battery terminals with it just sitting there. Started the car up and measured 12.3 volts across the terminals.
formatting link
about 12.2-12.3 volts between the black wire on the left andthe red wire on the right while the engine was running. I didn't knowwhat I was doing, but figured I'd throw that out there since I didmeasure there also. With just measuring across the battery terminalsand seeing a drop in voltage with the engine running is that enough todetermine the alternator is bad or is there any other testing I can doto narrow down the problem more? Thanks for the help!!! I didn't dothe steps you listed below because I'm not sure there's any point indoing them given the voltage reading I got on the battery terminals.Travis

"Stupid people are funny." - me

Reply to
Shag

Good test.

Correct- the alternator is not charging.

Question- does the dash "GEN" light come on when the key is first turned? Do you *have* a light?

The light is needed to get things going.

Speedy Jim

formatting link

Reply to
Speedy Jim

Less while running = fecked regulator or alternator, I'm sure Speedy Jim will chime in with more properiate values/lingo..

J.

Reply to
P.J. Berg

Hmmm... Funny you should ask... I noticed a "mystery light" the other day...

formatting link
on... checking... OK... I just checked... I turn the key to"on" and that light comes on... start the engine and the light stayson... even though the oil pressure gauge is reading about 40 psi (sothe light MUST not be for oil pressure) but when I rev it up to about4000 RPM the light fades out...and then comes back on as the RPMs diedown. Sure does sound like the alternator is shot from thatdescription, huh? I saw that light dangling there the other day andlooked under the dash but could not see anywhere that it waspreviously mounted so I haven't bothered doing anything with it yet.Sound to you like it's my "GEN" light and the alternator is toast?Anything else I could check? If I need to replace the alternator, cansomeone tell me which alternator to get? I mean if I get a stockalternator that fits a '75 would that be ok and have the righthookups? With this vehicle it's sort of hard to tell what parts areright for it. Hmm.. I should go dig through the paperwork that Timgave me with the rail. He even mentioned something about thealternator so maybe the paperwork in there would give me an idea ofwhat would work for a replacement. Thanks again for all of the help!

"Stupid people are funny." - me

Reply to
Shag

Yours has an internal regulator, which would have been stock in '75. Hmmmm. A qtr-century. You'd think they'd build 'em to last a little bit longer. LOL

All the replacement alternators now will have the exact same hookup. If you think you'll need more Amps, you could upgrade to a higher Amp unit.

Speedy Jim

formatting link

Reply to
Speedy Jim

Crap! More information... Just went back out there to look again. Turned the key and the light came on. Started the engine and the light stayed on. Revved up the engine pretty high and the light went out... and as the RPMs died down, this time the light stayed out. So I checked voltage across the battery terminals. 13.7 volts. Turned on the big bright lights and checked again... 13.55 volts. I'm

*positive* (I checked about 4 times before) that earlier with the engine running that the voltage dropped slightly at the battery terminals. Dangit. Now I'm not sure what to do. I guess I'll start by checking all of the electrical connections I can find to be sure they're clean and tight. I don't want to buy an alternator now since this seems to be an intermittent problem. :-/

"Stupid people are funny." - me

Reply to
Shag

It's possible that the brushes are worn down. If they don't make good contact, they can only start to conduct at high RPM. Or the slip rings could have some corrosion film after sitting so long. Worth a look to save a new Alt.

Speedy Jim

formatting link

Reply to
Speedy Jim

I drilled a new hole in the dash and mounted the light that appears to be the gen light just now. Made sure both wires were connected tightly to it. Also checked out the connections on the alternator itself. All 3 look/feel clean and tight. Started the engine and the light stays on until I rev it up a couple of times (all the while showing plenty of oil pressure on the oil pressure gauge so that light

*must* be for the charging system). Once I revved it up a couple of times the light went out and stayed out. I went back and measured about 13.9 volts across the battery terminals. That didn't drop much at all when I turned on the headlights. I drove it around the block a couple of times and just as I was getting back it started to run rough again. I checked the battery voltage while it was running and it was actually just a little over 14 volts. So while it is running all rough, the charging system seems to be doing ok.

Do you mean while the engine is running? What kind of voltage should I see across the two terminals on the coil with just the key turned to "on" in the ignition? Is there something I should measure at the coil while the engine is running?

You mean measuring the voltage across the two terminals of the coil?

Could I be seeing this problem even with the headlights off if this was a problem with the headlight switch? Is it "normal" to start your car up "gently" and have the generator light stay on until you rev the engine up a few times? I don't recall seeing that behavior with other old VWs I've owned. Sorry for all of the stupid questions. The weather is just starting to get nice around here and I'd love to be able to drive the rail around and enjoy it some without worrying about it letting me down and stranding me somewhere. Thanks. Travis

"Stupid people are funny." - me

Reply to
Shag

Sorry we got off in so many directions:-(

I suggested measuring the coil voltage because of the trouble you had getting the engine to start. That measurement would be from chassis to the + term (Blk) on the Coil. Should read ~12V with the key ON and *also* when turned to START.

The GEN light only going off after hi rev is a separate problem. (I suspect brushes.) But as long as it does go off and the battery is now charging, you might let this problem go. Speedy Jim

formatting link

Reply to
Speedy Jim

Why isn't your GEN light in the speedometer? Do you have an aftermarket speedometer instead of the OEM one? If you have an OEM speedometer, there should be lamp sockets for both oil pressure and generator voltage.

Reply to
Red Bug

Yes, it's a stock speedo. I didn't see any way to fit this light into a socket in the back of it:

formatting link
looks kinda cool on the dash, anyway. :)Now if I can just figure out why it starts running so rough that Ican't keep it running and have to turn the engine off and let it sit afew minutes before it will clear up again. Maybe it's a fuel kindaproblem after all...like garbage in the tank or carb or.... I'mPOSITIVE it's not the fuel tank getting a vacuum in it because one ofthe times it was running rough I completely removed the cap. No"whooshing" sound when I did that and it continued to run rough withthe cap off. I wonder... I just replaced the fuel filter with thatbig bulky filter... never seen a fuel filter like the one I just puton there before.... I think I may put an el-cheapo clear filter on it(not between fuel pump and carb) and run with that a few days. I hateto start guessing and buying parts to try out, but if I'm going toguess then I might as well guess at the cheap parts first. :-/ "Stupid people are funny." - me

Reply to
Shag

It "could" be the coil, crapping out on you when it gets warm, have you got a spare to try? Any 12Volt coil will do for a test..

J.

Reply to
P.J. Berg

No, I gave away about all of my spare VW parts to the guy who bought the LCB. Unless you count a wheel or two under the house or a hubcap or three. I was thinking about that, too. The coil on it now looks like a JC-Whitney special... Yeah... here it is:

formatting link
course I slightly modified it...
formatting link
the modification I made to it would be easily transferedover to a replacement coil... ;-) "Stupid people are funny." - me

Reply to
Shag

One wouldn't use the lamp you showed us... there is an internal lamp for GEN in VW stock speedometers -- there is a spot to shove a fairly small bulb and holder into the back, with a terminal to attach a wire.

It ought to be RED too, not green which was the old colour for the low oil pressure warning in early bugs.

What year is the speedo from? I see that even a late one from '72 to '77 still had the GEN lamp in the speedo...

See:

'73 to '79 too!

Sounds like it never left the speedo... I looked at all the OEM style speedos at Wolfsburg West and they all have GEN and OIL warning lights at the bottom of the speedo on either side of the turn signal indicator.

Should be down low along the bottom opposite from the oil pressure lamp socket.

Reply to
Red Bug

I'm really not very concerned about keeping it "correct." Have you seen my "vehicle?" Here's a picture of it:

formatting link

"Stupid people are funny." - me

Reply to
Shag

I guess it was important to see this warning light really well, and so a P. O. decided to skip the factory OEM option and went with a nice big lamp instead...

Another idea would be to return to the stock GEN lamp spot in the speedo, but use a "super bright" green LED... Then even a "flicker" of a signal would really get your attention as the GEN warning would blink at you every time it got over the diode threshold voltage of the LED which is small enough that it ought to be enough... Thoughts anybody?

Having it right in the speedo is actually a good location because you are more likely to view that spot on the dashboard vs. some far off location that you might drill out.

Reply to
Red Bug

I drilled the spot for it right between the ignition switch and the oil pressure gauge. It's closer to me than the speedo is, and very visible.

"Stupid people are funny." - me

Reply to
Shag

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.