I think I’ve fried my Pertronix - how do I test?

[Red Devil]

Like a fool I’ve just reinstalled my engine (62 bus but converted to 12v with alternator and 1600 engine) but realised I had one wire which connects to the coil “left over” and I wasn’t sure which side it connected to. As it was black I went with the -ve side!

On the +ve side we’re the red Pertronix wire and the one which runs to the fuel cut off solenoid and choke. The only -ve wire was the black Pertronix wire.

Hence, I tried to start the bus but it would not fire. Fuel getting through ok. I have no spark when grounding a plug on the block. Having dug out an old wiring diagram I now think the wire I wasn’t sure of should have gone to the +ve also. Would this likely fry my Pertronix hence no spark?

The wire appears to run from the rear to the front of the bus so doesn’t connect to anything else in the engine bay.

I’m happy with mechanics but not electrical so is there an easy way for me to check/test the Pertronix unit? Of course it could be something else but my gut feeling is this is now an expensive mistake.

Thanks for any help or advice which can be offered.

Steve

[easy e]

The forum search function is your friend.
You don't need to test it... just get the 'ol wallet out again.

[Red Devil]

Thanks. I didn’t actually reverse the wiring for the Pertronix. I connected a different wire which I think should have been on the positive side to the negative side. Does this have the same impact?

Thanks

Steve

[easy e]

To test it...
Hook it up like it's supposed to be... and check for spark.

If no spark... check your coil.

[flemcadiddlehopper]

You could also put a spark tester on the coil and hold a soldering iron near the distributor. The electromagnetic field of it will trigger the pick-up and make the coil fire. No spark, bad pick-up, or coil. Test light between neg wire for the coil and power. If light flickers with same test, bad coil.(good pick-up and module).

Gordo.
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[Glenn]

Youtube has tons to videos... here's one.


Link

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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

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[Red Devil]

Many thanks all. New unit fitted today and up she fired. Just need to take it on a run now and check everything else I’ve been fiddling with seems to work ok.

Appreciate your time in responding to my questions.

Steve

[telford dorr]

Interesting. This confirms what I have long suspected about these modules:

- the coil drive is "on" by default. Thus, with the key on and engine not running, power is being dumped into the coil, heating it up. So; either start the engine or turn off the key. Otherwise, you'll cook your coil. If you must do testing with the key on and the engine not running, unplug the red module wire from the coil.

- these units pulse the coil off for a moment when a magnet passes the sensor, then immediately turn the power back on again. I suspect that you'll find that the "off" time is fixed (need to confirm with a 'scope). This means that there is no fixed "dwell angle" like a points ignition has. I suspect it is optimized for top rated engine speed, and the effective dwell angle is likely very much greater than stock as the engine speed decreases. This means that the coil will run MUCH hotter than it would with a points setup. Can the coil take it? Apparently, for a while....
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[PookAndThePack]

So, I did fry it. But now, with new distributor in, an empi, it still won’t start. The coil test to read 3.0 ohms. Spark going to distributor. What could I have fried?

[Glenn]

[PookAndThePack]

Put in old vacuum advance distributor. Spark gets to spark plugs. (Pulled number 3 out and grounded it while friend cranked engine. What else could I have fried? It’s a 67 bus, but engine is code AK , so from 73’. Still won’t turn over. Is there something electronic in fuel delivery system that may have fried? I’ve not check to see if fuel pump is working.

[srfndoc]

Check your points gap. Did you statically time it with the new dizzy?
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RPM=(MPH*336* (R&P*4th*1.26))/Tire Diameter in inches

[telford dorr]

In case one of the distributors was a "009' style, keep in mind that the wire positions in the cap are 90 degrees different than a stock distributor...
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[wcfvw69]