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Hello. I have an 84 with no title yet that would not spark and I will not work on until I get a title. Now I have an 86 spider that will not start - I see a very weak spark off the HT coil wire. Voltage from the + terminal of the coil to ground is over 12 volts with key in the on position and it drops below 9 volts when I crank the car over. When I check the voltage back by the FI ECM it stays over 12 volts there even when cranking. I checked the two sensors and they are both over 1000 ohm. I have cleaned all grounds and everything looks good. Car cranks great. When I bought the car it did not run and the last owner thought he had a bad starter but I found that was just a bad ground strap conection - I cleaned that up and it turns over everytime. I added a new cap and rotor but zero spark at the plugs and just a weak yellow spark off the coil wire when I hold it near a ground. Thanks again, Mike
 

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12V at the fuel ECU during crank is VERY good (almost too good; exactly where were the voltmeter test points?) but only 9V at the coil is not. That is a massive voltage drop! A possibility here is dirty contacts in the ignition switch.

I've sent you a PM.
 

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The 12 volts is at the inline fuse near the relays under the package tray. It is also at the main relay (big red wire) when I crank the engine. The 9 volts is when I check from a ground to the + side of the coil with all the wires still conected. I tried the coil from the 84 with the same results. One difference with the 84 was that it only had one wire (green/black) on the + side of the coil where my 86 has two wires on the + side. Thanks again for your help. My mechanic is nervous that now I have two non running Alfa's.......
 

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The second wire on the coil + powers the electric VVT (Variable Valve Timing or variator) solenoid. Your 84 has a mechanical VVT; no wire needed.

Those voltage test points are good ones. So there is a huge voltage drop in (at least) the ignition circuit. A possible (and common) problem is corrosion in the junction block (left inner fender). All the main circuits for the vehicle connect here. Removing each wire and cleaning them has been known to solve many an electrical issue.
 
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