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sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5998
Location: Brooklyn
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 Posted: Tue May 17, 2016 11:53 am Post subject: Re: 67 Bug won't start |
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| kshan7 wrote: |
| The coil put out 12.3 volts with the key on and 6.5 volts while starter was turning engine over. No other electrical load present. Try a new coil? |
The coil doesn't "put out" voltage. If you're measuring at the coil + terminal and only seeing 6.5v there while starter is turning, you're measuring the voltage that is going into the coil from the ignition switch. Below about 9.6v or so the coil will not be able to generate a spark. That low a number means either your battery is crap or you have a bad connection somewhere to include the battery terminals, battery ground strap, transaxle ground strap or anywhere in the pathway of the wiring from the battery to voltage regulator to headlight switch to fuse box to ignition switch and/or back out from the ignition switch to the coil. That is a SEVERE voltage drop.
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kshan7
Samba Member
Joined: April 09, 2016
Posts: 24
Location: Alabama
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| Posted: Thu May 19, 2016 8:19 am Post subject: Re: 67 Bug won't start |
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| Well, I had to take a break for a few days. So, what could make the voltage out of the coil vary? I can only come up with the ground. I'm looking at the wiring diagram (thank you Rob and Dave) and I as far as the coil goes, the ground strap to the tranny seems to be the only one that could affect it. Am I missing another ground that could matter? I'm going to double check that ground and see what happens. |
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kshan7
Samba Member
Joined: April 09, 2016
Posts: 24
Location: Alabama
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| Posted: Thu May 19, 2016 11:31 am Post subject: Re: 67 Bug won't start |
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| Ground is good. I have run a wire from my battery straight to the + side of the coil. That should eliminate any losses of voltage from the ignition circuit. Turns over great, still won't fire. Just to check again, ran a + wire from my explorer to the coil and a ground wire from explorer to the engine. Cranked right up. Again I have put a new battery in the bug and no cranky. What am I missing?????? |
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EverettB 
Administrator
Joined: April 11, 2000
Posts: 69829
Location: Phoenix Metro
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| Posted: Thu May 19, 2016 5:22 pm Post subject: Re: 67 Bug won't start |
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| kshan7 wrote: |
| Ground is good. I have run a wire from my battery straight to the + side of the coil. That should eliminate any losses of voltage from the ignition circuit. Turns over great, still won't fire. |
What's the voltage at the coil before and after cranking when you did that?
I would guess it's still low and it's one of the grounding points mentioned above by sjbartnik
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kshan7
Samba Member
Joined: April 09, 2016
Posts: 24
Location: Alabama
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| Posted: Fri May 20, 2016 6:21 am Post subject: Re: 67 Bug won't start |
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| Voltage is 12.3 with key on and between 4.5 and 6 volts when cranking. |
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OLD VW NUT
Samba Member
Joined: February 23, 2011
Posts: 2776
Location: High Desert of Washington 98823
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| Posted: Sat May 21, 2016 10:21 am Post subject: Re: 67 Bug won't start |
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Your wiring has voltage drop somewhere between the battery and the coil. Have you measured the voltage available at the fuse panel as has been suggested by prior posters? You can measure the voltage at the coil till the cows come home but that won't give you any answers. Measure the voltage AT the fuse panel - starting with that big red wire that comes from the battery. You need to trace & measure each segment in the wiring path to the coil - including the ignition switch (which I suspect may be the culprit) - simply measuring AT the coil only confirms what we/you already know. Start closest to the battery and follow that large red wire from the battery to the front fuse panel - measure wiring at each juncture AND each side of every connection/terminal. That big red wire could very well be the problem - 49 years of continuous amperage flow takes a toll on wires. Very few of these cars have unmolested wiring - installing after-market radios amps fog lights etc all take their toll on the original wiring harness and may create more current draw than the wiring was designed for. I've found more problems with 'stock' 67 and up cars (first year of 12v) than any 6v converted to 12v. This is because the wiring is heavier than 12v cars. 6v cars that retain the 6v system usually have one common problem
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kshan7
Samba Member
Joined: April 09, 2016
Posts: 24
Location: Alabama
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| Posted: Wed May 25, 2016 11:28 am Post subject: Re: 67 Bug won't start |
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| First of all, many thanks to all. I learned a lot. The bug is fixed, it now starts and runs like it is supposed to. Thanks to air-cooled.net, they suggested I replace my ground cables even though they were tight. I put a new ground cable from the battery to the frame and it started right up. I guess the bad ground was causing the voltage drop. Anyway, again, thanks so much! |
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