My bug wont start

[Krazziebug72]

Hello Everyone,

I need some tips on what to do here so I will explain what happen today. I have been driving my 72 super beetle to school for the past 2 weeks. Today it has just shut off on me while I was driving doing about 40 mph. I pulled off to the side and check the engine and I have found a wire that was hook up to the ignition coil have burnt up, I'm not sure what this wire is for but I know its not the factory ignition switch or the wire that goes to the distributor. I have replaced the wire and the ignition coil and still when i go to crank it up, it will keep turning over but wont start, at times it will start for a couple of seconds then shut off. I'm am still learning the mechanics so please excuse me if I don't explain myself well. The engine I believe is a 1.6 and sounds great when she is running. If you all can give me a direction on what to check up next I really would appreciate the help.

[Aussiebug]

Hi Kraziebug,

It does sound like you have an electrical problem.

There should be a black wire coming out of the wiring harness connected to the + terminal of the coil. This is the main power supply to the ignition and other engine systems. There should be another wire(s) from that terminal to the auto-choke and also to the idle shut-off solenoid in the side of the carb. If your car has reversing lights, then there will be ANOTHER wire on the + terminal of the coil which goes through an inline fuse (mounted on the fan shroud) which then goes to the tranny switch for the reversing lights.

The minus (-) terminal of the coil should have only a single wire (usually green) going into the condenser inside or attached to the distributor.

You need to get yourself a cheap digital multimeter ($15-20), then do these very simple tests.

1. Set the multimeter to a 20 volt scale or thereabouts - something above 12v.

2. Turn on the ignition switch and then use the multimeter to test for power at the coil - place the red multimeter lead on the + terminal on the coil and the black multimeter lead on bare engine metal. You should see 12v. If not you are not getting power to the ignition system. As I said above, the power comes in via a black wire from the wiring harness - the other end of that wire is at the ignition switch itself.

3. If you have power, next test is to check the coil itself. Remove all wires, set your multimeter to a lowish ohm setting and test between the + and - terminals on the coil. You should get about 4 ohms. If so, that part of the coil is working. If you get only 2 ohms, then you have a low-resistance coil which is best suited to a Pertronix or other points-replacement module. The standard ignition system works better with a 4 ohm coil - it helps stop sparking at the points.

4. Now we test the high tension (voltage) side of the coil - use a higher ohm setting and test between the - terminal and the centre post on the coil. You should get about 10,000ohms. If so the coil is good.

5. Make sure your points are opening when you turn the engine over by hand (ignition off) - 16 thou is the correct amount.

6. Now connect everything back up, and then pull the centre wire off the distributor, hold it with insulated pliers (and use rubber gloves - an 18,000v shock is no joke) close to some engine metal and get some one else to crank the engine for a few seconds. You should see a steady stream of fat blue sparks. If so, the ignition system is working well. Thins yellow sparks are not so good - this can mean your condenser is on the way out or even the coil (even if the ohms tests were OK). You can also test each individual plug wire the same way - you'll get less sparks for each plug of course, but should still get fat blue sparks.

Hope that helps.
_________________
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com

[ashman40]

This is Speedy Jim's simplified diagram for the engine compartment:

Notice the black wire from the harness in the upper left. This is the source of power for the ignition coil. It connects to the #15 (+) terminal on the coil.
The other two connections from the (+) terminal are:

idle cutoff solenoid + electric choke

reverse lights

On the other side of the coil is the green wire from the distributor points+condenser. Other than possibly a wire to the aftermarket tachometer... nothing else should connect to the (-) side of the coil.

I suspect the wire to the carb's idle cutoff solenoid was the one that melted. You need to repair this. The Solex carbs that have the cutoff solenoids will not idle with the solenoid disconnected.

Try to understand why the wire melted. If you just repair the melted wire without understanding the cause, it may just happen again.

As a precaution, you might consider installing an in-line fuse at the front end of the black ignition wire. It connects at the fuse box but is not protected by a fuse.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Krazziebug72]

Hey guys,

I want to say thanks to the quick replies on my situation. So I'm trying to understand why the wire fried in the back so checked all the wiring up front by the fuse holder to make sure nothing was out of the ordinary. I have notice that I'm not getting power to the back from the wires that connect to #15 when I turn the key to on position. I notice that my fuel gauge is not working or radio. All the fuses have been checked carefully up front and the one under the back seat by the regulator. The wire that burned up came from the right side of the engine next to a factory connector that runs under the body next to what I believe is the starter. I followed the wire and it burnt to a spade connector that someone had installed. I check the remaining wire and it doesn't look damaged so I replaced the wire from that point back to the ignition coil. Is it possible that I can upload a picture here to show you all what I see?

[Krazziebug72]

Alright, I have uploaded a picture in my gallery for you all to see the wire I am talking about that burnt up. I highlighted the wire in yellow. This wires runs underneath the right side.

[ashman40]

[Krazziebug72]

http://www.thesamba.com/vw/forum/album_search.php?...ts=summary

Hey again,

Here is what I did yesterday up front. Ashman40 I will go test on that fuse holder when I get back from work, Thanks for all your help.

[ashman40]

[Krazziebug72]

Hey,
I have had no luck today figuring out my problem. I have included pictures of the wires coming out of the harness on the left to the ignition coil. The pictures that are taken underneath the vehicle was the black wire that burnt I followed on the right side. If someone can take a look and give me some feedback on what it might be. The black wire ran to the back of tran I think, I have a picture with green highlight where it led to. I have notice on one of the picture that I have yellow highlight some wires. I didn't see them while I was under the car. Anyone have idea what they might be. I want to thank you all again how much I appreciate the help.
http://www.thesamba.com/vw/forum/album_search.php?...ts=summary

[ashman40]

Here are some of your pics and my comments:

This is the reverse light switch at the front (front of car) of the trans.
If the black wire that burn up was one of the two wires here, it likely means one of them was grounded.
The black wire starts from the ignition coil #15 (+) terminal; goes to the fuse holder on the fan housing; goes around the right side of the fan housing and out the hole in firewall tin. Before going through the hole it joins up with another black wire. The other black wire is just the return. So two black wires run to the reverse light switch (one for each prong of the switch).

The return wire should connect with this splitter once it is back inside the engine compartment:

This is where the single return wire splits into two separate reverse light outputs. This is show in the bottom right of Speedy Jim's diagram.
Yours looks disconnected. If the return wire is touching ground you may have just found your short!

This shows that someone cut and then repaired the wires to the ignition swicth. That is definitely not the best crimp job I have ever seen. These wires carry a lot of current and need to be high quality connectios.
If it were me, I'd remove the crimp connectors, solder the wires together and then heat shrink to protect them.

This pic shows that the PO installed a "Ford" relay for the starer solenoid (hard start relay).

And lastly, I would comment that the wire that brings power from the ignition switch to the ignition coil (+) terminal is usually a thicker gauge wire. In your case the wire looks to be the same gauges as all the rest.
Where does that white wire spliced into the same spade as the black wire run to?
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[sb001]

[jwold]

It doesn't look like you have your oil pressure switch hooked up?

[SBD]

In the last engine pic in your gallery, the one before the 3 car pics, there's a wire with a yellow crimp connector just sort of lying on the sheet metal on the left side toward the bottom. Not sure what it is, might be the oil pressure sender wire. Whatever it is, it could be shorting to the engine and causing a problem.

[Krazziebug72]

Hey folks,
I have been busy with my classes these past few day, but I have been doing research on 72's wiring diagram. The PO has cut a lot of wires and only has tape bairly holding most of it together in the front grey wire harness. I think that wire that burnt up might have damaged my ignition switch since there was no inline fuse on that wire. I am going to replace the switch and see if that fixes solution. Im hoping I can figure this problem out, my other option is to buy a new wiring harness and replace the entire wiring system and start from scratch, at least i will know that all the wire are in one piece and protected with proper inline fuses.

[ashman40]

[Krazziebug72]

Hello all,
It has been a crazy week for me with work and school. I have found a new OEM ignition switch that I will use to replace the old one. I have pulled the steering wheel off yesturday but started to rain so hopefully today will be a better day to work on it after class. I will keep you all posted on my progress. Now just so that I don't make the same mistake as the PO, do I put my inline fuse on the black wire between the switch and the fuse box? What other precautions do I must take in consideration so that I prevent future burn ups? Thanks again

[Krazziebug72]

The new switch does not have any fuse on it. All the wires on this ignition switch is solder together also just so that you know what i have.

[ashman40]

[Krazziebug72]

http://www.thesamba.com/vw/forum/album_page.php?pic_id=1139084

Here is my old switch. I have already installed my new one before I seen your last post. Its pretty much that end piece without the plug part, instead all the wires solder to that switch. I'm going to wire it up now, but I notice on the old switch that its broken at the end so I hope that this is the problem. I will let you know after I finish.

[Krazziebug72]

Well rain or shine doesn't matter to me. Just got done wiring up the switch and put an inline fuse where the last wire burned up. I cranked it up and it starts YAHOO!!!! Done it about 3 times and starts right up and stays on. I will take it for a drive when it stops pouring down rain here. Well I hope this fixes the problem and I want to thank you all so much for the help, I couldn't done it without you all. I will keep you posted.

Thanks again ashman40 for the constant help and images.