Starting problem

[steve s]

When I try to start with my ignition switch the motor turns over but won't start. but when I jump the starter relay switch and leave the ignition on it starts up. The relay is good. This car is not stock it's a 73 charger with a 440 and sniper fuel injection. I put painless wiring harness in it. The wiring was all tore to hell in it. so I'm doing the best I can. Any suggestions would be helpful thank you.

 

[tonysrt]

You might not be getting voltage in the crank position, but you get it in the run position. Try and check voltage in that start position. Put a voltmeter on the Positive side of the coil, ground other side and see if you have volts when in the start position.

 

[70chall440]

Mopar ignition switches have 2 sides, IGN 1 and IGN 2 (one wire is blue and one is brown). One provides power to the starting system and the other to the run system. It was done this way I believe to reduce electrical draw during starting. That said you need a feed from each side to your EFI system to run.

 

[Nacho-RT74]

on stock system, the power flows like 70Chall440 mentioned from ign switch but as far ballast is conected both circuits remain powered, just at diff voltage levels on each stage.

Now, if you remove ballast will need to splice both wires together to get power on both stages (run and start)

 

[451Mopar]

As 70chall440 mentioned, the ignition switch has an IGN1 which I think is the normal RUN position usually Blue wire (not sure on the specifics for the 1973 model?)
This is likely the (correct) circuit you have powering the Sniper. The problem is when the key it turned to the START position, power disconnects from IGN1 and goes to IGN2 (and also the terminal that switches the NSS relay for the starter.) On the cars I tested IGN2 and the NSS power are not connected. Important because IGN1 and IGN2 are normally connected together so the Sniper gets power in both RUN and START key positions. This bypasses the ballast resistor, so the stock ignition system is usually changed to a type that does not need a ballast resistor. Also, with the Sniper, you would want the EFI to control ignition timing.
The ballast resistor could be retained if wanted, but the IGN1 and IGN2 would have to be routed through the Anode side of Diodes before connecting the cathodes together and then the Sniper power on signal wire (I think small pink wire?)
I am going to experiment with the cheap Optocoupler isolation relays to make relay switched power to the Sniper and will ignore short power dropouts from the ignition switch.
Basically the relay module, diodes, and a capacitor.