How many volts at coil? 72 F100

[jlb]

My son was driving the truck the other day. Motor shut off and would only run with lots of gas. Then wouldn't run at all. Stock 302 v8. 3 speed. replaced plugs, cap, rotor, points and condenser and the coil. when you measure the voltage at the coil when points close voltage drops to 6volts. If you run 12volts into the the coil with a jumper wire - The truck will run with lots of gas, but will not idle. Or if you disconnect the jumper wire it Shuts right off. FYI - we know very little about points.

Any thoughts? Truck ran perfect before this. This is his daily driver..

Thanks in advance

Jeremy

[sargentrs]

You should get at least 9v+. Go get another condenser. They're bad about being bad right out of the box. In my '64 Fairlane, I went through 2 in 48 hours. When the 3rd crapped out in a week I gave up and switched to electronic ignition.

[jlb]

So, Just with the key on it should register at least 9 volts? Is that the proper way to measure?

[Ranchero50]

With the points closed you should read 0 volts from coil - to batt - and somewhere close to that from coil + to batt - With points open you should read batt + from coil - and the same from coil +. The key is voltage from coil - to batt - should be 0 when closed and batt + when open.

There's a long resistor wire that keeps the wiring from burning when the points are closed with the key on. It'll drop the voltage between the coil primary windings and the resistor wire depending on the resistance of each at coil +.

I also agree wholeheartedly about the condenser. I've found old ones from junkyards work better than new ones from the Autoparts places.