Dune buggy electrical gremlins at coil....?

[badnessbus]

Hi,

I've been working on VWs for quite a while. We recently moved to Baja, Mexico and picked up a fiberglass dune buggy. 1964 pan, 1971 engine.

I tuned it up when I bought it, and it was running great for a few months until the front transmission mount broke.

I pulled the engine, slid the tranny back and installed a solid front mount. Put it back together with new battery, and it cranks like crazy, but won't fire, unless I connect a second 12V source to the coil. I've been scratching my head over this for a couple months, and just can't figure it out.

It has the Pertronix II distributor and Flame Thrower II coil that goes with it.

I've narrowed it down to low voltage at the coil, but why? And how is it related to replacing a front tranny mount. I made sure the tranny ground strap is in place.

Here's where I'm at:

- Disconnected the electromagnetic cutoff valve from the coil.

- Disconnected the choke from the coil.

- The only things connected to the coil are the 12V from the ignition and the + and - distributor wires.

- With + distributor wire DISCONNECTED from coil and ignition on, I measure 12V at the coil + terminal.

- After connecting the positive distributor (pertronix) wire to the coil and turning on the ignition, the voltage at the coil + terminal is just under 2V.

So for some reason the voltage drops when I connect the distributor to the coil, and it is not enough to fire the coil.

If I take a small motorcycle battery and run the negative to the VW chassis, and the positive to the + terminal on the coil, the buggy fires right up!

So with 12V at the coil + terminal it will run fine, but I can only get that with an external battery connected to it.

Is this crazy? Am I missing something obvious? I'm almost at the point of installing a relay to supply another 12V source to the coil when the key is turned on. I'm sure that would work, but that is not really a fix, more of a work-around

Anyway, thought I'd turn here for some advice...thanks....

[MrGoodtunes]

[Dale M.]

If voltage at coil drops below about 8-9 volts when cranking module will probably not fire coil...

Might connect test lamp to coil negative and ground and see if it blinks off/on/off/on as you crank starter...

Might also be poor wiring from ignition switch to coil, voltage drop from bad connection or to small a gauge wire can also be a problem...

Dealing with a buggy there is no guarantee that any of the wiring is good, most people who built buggy's did not understand quality wiring, much was just pieced together crap....

Run a temporary 14 gauge wire directly from IGN terminal on switch directly to coil positive (disconnect
old wire) and try that, if buggy does not start, then pertonix unit has probably gone south...

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[badnessbus]

Thanks. It runs fine with an external battery connected directly to the coil, so I'm thinking the Pertronix is fine. I'm betting on the old ignition wire being the culprit, and perhaps moving the transmission put some extra tension on it.

You are right, the wiring in this thing is a rat's nest. Some day I would like to clean it up. Without the usual access behind the dash from inside the trunk, these fiberglass buggies are a real pain to work on anything electrical under the dash.

For now I'm going to try installing a relay with signal from the ignition wire, and 12V direct from battery with a fuse. I've read on some other posts that has been done. Eventually a new wire from the ignition.

[badnessbus]

Ugh, so strange. I installed a relay, positive direct from battery with fuse, signal from the ignition switch, and still nothing.

The positive wire from the ignition is 12V until I connect either the Petronix hot + wire to the coil, or the electromagnetic cutoff switch at the carb. If both are disconnected, I get 12V at the coil input + wire. When I connect either the Pertronix + or the + to the cutoff switch at the carb, the voltage drops to near zero.

[MrGoodtunes]

[badnessbus]

Yes, a external battery on coil and it fires right up. And if I remove the external battery while it's running, it dies.

So I'm sure the reason it won't start is that there is not 12V at the coil when the ignition is turned on (running or not).

Hmmm, I hadn't thought about the alternator being part of the puzzle. It has one of those Motorola alternators with the little white box on top, something I hadn't seen before. I will do some more testing with the alternator disconnected, and also check to see if it's charging (it was before I pulled the engine).

[MrGoodtunes]

[Dale M.]

MR GT is on track....

Really thinking there is a bad supply from battery to IGN switch...

Or bad Ignition switch...

Or bad supply from ignition switch to coil...

Also if you connect solenoid and choke either one of these may be shorted internally and pulling voltage down to a point so low Pertonix fails...

How does other electrical items function like headlights and turn signals?

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[rayjay]

Dale probably nailed it. Your ign switch most likely has internal issues. The brass contacts inside do corrode up and cause issues. If you look closely at the back of the ign sw on my test stand you will notice that the crimp tabs have been straightened and there are now screws holding the bakelite portion to the zinc body of the sw. It was giving weird problems so I took it apart and the contacts were growing green crud. Cleaned them up with sandpaper and put it back together and works like new. The zinc metal tabs break off if you try to recrimp them hence the tiny screws.

FIRST !!, check the wiring ! If there are crimp connectors give the wire a good tug to see if the crimps have lost their tension due to corrosion. Dale's input on this forum inspired me to invest in some decent crimp tools and connectors. Now wiriing is fun !!

[rayjay]

ETA, first thing I would do is make up a new 12 ga wire from the ign sw to the coil. If the problem persists then the ign sw is probably the culprit.

[badnessbus]

Just to close this thread, the local VW guy in town replaced all the wiring and the car has been running great. Labor is relatively inexpensive here in Baja

But now having charging issues with the new wiring, leading to my next thread...

[Dale M.]