Engine fires over but as soon as I let go the key engine dies

L

LutzCoyote

Member
I’ve got 304 in a 72 scout. Today I replaced the carb with a new Holley 7448. Now when I try crank the engine it fires but as soon as I let of the key it dies. I have spark and I have fuel so for the life of me I can’t figure out what’s happened.
Additional I check the wire going to the start think one may have a bad connection but I’ve had no luck.

Thanks for Any assistance you my can provide

Sam
 
While cranking, the S terminal on the starter supplies 12 volts to the coil. With the key in the run position, the coil is supplied with a reduced voltage through the resistance wire from the ignition switch. Verify that you have between 12 and 8 volts at the positive coil post with the ignition switch in run. If not the resistance wire is open.
 
You can temporarily rig a jumper wire from the battery positive to the coil positive and see if that gets you lit off. It is very important that you DO NOT leave this jumper hooked up any time the engine is stopped and don't use it as a lazy bandaid either. It is only for diagnostic purposes. If the engine starts up and runs with the jumper, then you know that something is wrong somewhere with your IGN switched feed to the coil. Then you just have to find the break.
 
Just wanted to update you guys, You were correct the resistance side was open and once I found where the wire was broke and fixed it everything work perfect.

Thanks for the assistance.
Sam
 
Thanks for updating. It's important that the length of that resistor wire not be modified. It should look a good deal longer than what you would actually need to span the distance between the firewall and the coil, with the excess length doubled over and over again on itself. That length is what provides the ballast resistance to protect your points and coil from overheating while the engine is running.
 
Wow, You learn something new everyday. Fortunately I thought there must have been a reason for the additional length so I made the replace on the same.

Thanks ScoutBoy74
 
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