Hey everyone.

I am having some electrical issues with my 73 Dart Sport, and I thought it might be a good idea to ask others for input on the situation.

A little background: the Dart's been getting very poor gas milage (~10mpg, city or highway) since I got it running last August. I kept thinking it was something to do with the carburetor (never thought to check for ignition problems). Just before I made the switch the throttle body fuel injection in an attempt to get better mileage, it occurred to me to check what kind of spark I was getting. Turns out, I was getting a very weak (yellowish/orange) spark. Eventually, I checked the voltage at the coil. It was receiving ~2Volts when the ignition switch is in the Run position, and ~4 Volts when cranking.

Of course, I was (and still am) amazed that the car starts/runs at all. I've checked with different meters, including a Fluke meter, and all read close to the same, so I am sure that the reading is accurate. I did try checking the voltage with the negative lead connected to the battery, and read a slightly higher voltage (~3.2 Volts).

The red wire bringing power to the ignition switch is carrying approximately 12.7 Volts. The blue wire (ignition 1) and black wire (accessory) both read ~11 Volts in the Run position, and the yellow wire (ignition 2) also reads ~11 Volts when the switch is in the Start position. The brown wire is confusing me a little. It reads ~4 Volts in the Run position, and ~11 Volts in the Start position. I thought the brown wire provided power to the starter, but, if that is the case, I don't know why there would be any power going through in in the Run position.

The ballast resistor (4-pin) read ~5 Ohms across pins 1 and 2, and ~1.5 Ohms across pins 3 and 4. I have replaced it, and the resistor had almost identical readings, which are close to what my direct connection book specifies (5 Ohms and 0.5 Ohms, respectively).

I swapped the ignition module with a new one (just to be sure), and have a ground wire from its case to the negative terminal of the battery. Resistance across the wires from the distributor was ~400 Ohms.

I think I have included most of the important information, and I don't want to make this post much longer than it already is (or no one will read it ). I am assuming at this point that there is a bad connection, or a break in a wire somewhere that I am missing, and that I will end up having to replace most of the ignition system's wiring.

If anyone has any ideas on what the problem may be, please let me know!

Thanks!
-Jashen

Have you checked all your grounds? Battery to block. Block to body? Checked you bulkhead connector?

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50 chrysler,54 Plymouth, 64 Valiant conv 4 speed, 66 Valiant V8 wagon, 70 Challenger R/T 440+6 conv 4 speed,80 Colt, 98 Neon ACR,84 Honda V45 Magna
Taking care of 57 300C conv,48 T&C conv. Missing my 67 GTX and 36 Ply coupe

Good
Should have 7 or 8 volts running, full 12.xx volts when cranking with stock coil.

Yes break & remake all grounding connections so that they are electrically sound. Next test for voltage drop in each conductor from terminal to terminal. In other words ballast resistor to coil, and the like. Each conductor and or connection will introduce resistance into the circuit reducing delivered voltage to a given device, in this case your coil. You will need to trace from battery to amp gage to ignition switch back out to ballast resistor, over to ECM and to coil.

Clean battery terminals, and replace any damaged cable clamps or nasty battery cables.

Connections at bulkhead connector are often corroded (white or green stuff), and introduce a lot of resistance, sometimes enough to melt its housing.

Also check the coil's resistance, Should get around 0.75 to 0.81 ohms between + & - primary (low voltage) terminals, and between + terminal and center high voltage out-put socket ( secondary) 10,000 to 10,000 ohms on stock coil.

Print off a copy of wiring diagram, attach it to a clip board. Follow diagram, crossing off each leg of each ignition circuit as you go so you don’t miss something, and don’t replow the same ground. Make notes, and be prepared to replace wire & brass connections.
Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Thanks for the replies.

Weather permitting, I will start tracing wires tomorrow, replacing wiring and connectors as needed.

Looking at one of the wiring diagrams tells me that I was wrong about the brown and yellow wires coming from the ignition switch. The brown is the Start (ignition 2) wire, and the yellow ends up at the starter relay. The brown wire's voltage is close enough to what it should be when the switch is in the Start position, but I'm still not sure why it has 4 volts when in the Run position. Shouldn't it be at 0 volts then?

Thanks again!

-Jashen

Most likely it is "back feed" from the coil and not coming from the switch.

_________________
50 chrysler,54 Plymouth, 64 Valiant conv 4 speed, 66 Valiant V8 wagon, 70 Challenger R/T 440+6 conv 4 speed,80 Colt, 98 Neon ACR,84 Honda V45 Magna
Taking care of 57 300C conv,48 T&C conv. Missing my 67 GTX and 36 Ply coupe

Hey.

Just thought I'd post an update on what is going on.

I went through and replaced a lot of the wiring, bypassing all the connectors I could, and replacing most that I couldn't. I was sure I wired everything correctly (checked several times) according to the Direct Connection diagram.

The reading at the coil is now ~3.5 volts when the ignition switch is in the Run position. However, if I remove the positive wire from the coil and check voltage between it and the negative battery terminal, I read ~10 Volts. Not sure why that it is. Anyways, I am now getting a nice bluish-white spark. That's the good news. The bad news is that I am still getting ~10mpg highway (65-70mph) driving, and the engine is still running rough and going through about 2 quarts of oil every 70 miles.

I've decided at this point to pull the engine.

While it is out, hopefully we'll figure out what is wrong with it, and check performance on a dynamometer before putting it back in. I'll also work on a better wiring setup in the car.

Anyways, I just wanted to provide an update. Thanks again to everyone who offered advice!