Re: 1951 300 Starting Issue

Posted by HH56 On 2020/5/12 21:50:29

Assuming the battery is good and battery cable connections are clean and tight you can use a length of jumper wire to bypass the carb start switch and the neutral safety switch to see if the engine will crank without those switches in the circuit.

Use a wire that is about the same thickness as that already connected to the solenoid top terminal or about 14ga. You do not need to remove the existing wire on the terminal as it just goes to the carb starter switch and will not connect to anything else as long as the accelerator is not pushed down.

Temporarily run the jumper wire from the hot battery terminal and just touch it to the small terminal on top of the solenoid (make sure the Ultramatic is in park) and the engine should at least crank and start if the key is on. If it does crank then one of the switches is bad, out of adjustment, or has become disconnected.

If it cranked you can troubleshoot to see where the problem lies. Power flow is from the ign switch, down to the neutral safety switch located on the drivers side of the transmission, out of that switch and then back up to one side of the carb starter switch and out of the starter switch to the solenoid. With the key on you can use a volt meter and follow the power to and thru each switch. If you lose the 6v (as measured to ground) after going thru a switch that switch or wire is the suspect.

If still nothing happens with the jumper then the battery, a cable or the solenoid is the likely suspect. If you have one of the green knob battery cable disconnect switches in use those are notorious for failure when used on 6v cars.