Posted: 08/21/12 02:27 PM
Mustangs and Ford's virgin here, my 289 wont fire, got my 7.?? Volts to the coil but nothing at coil wire at cap? New coil by the way. All help greatly appreciated.
Posted: 08/21/12 04:44 PM
a few things.....
key on... power at the coil... could be 7 volts.. sounds a little low..
key cranking.. should be over 10.5 volts... as it comes off the starter solenoid at the I terminal..
the I terminal circuit inside some starter relays have failed... so check the voltage at the coil key on.. and key cranking..
pull the cap..... leave the rotor on... crank the engine.. does the rotor turn??? timing chains have had the aluminum with nylon teeth cam gears fail.. replacement cam gears
are the point contacts burned....
are the points opening and closing as the engine is cranked...
when the key is on... and the points are closed... the electrons travel up from the block through the distributer housing.. through the braided ground strap from the housing to the hold down screw on the points... through the contacts when closed to complete the circuit to the primary windings of the coil....
when this happens.. the primary winding creates a magnetic field.. as the engine rotates.. the points close and open... when closed the points create a magnetic field in the coil.. when the points open the magnetic field collapses through the secondary windings in the coil and a high voltage spark is created...
if the points contact faces are burned.. there will not be enough surface area to allow enough electrons to flow into the coil.. you won't get a spark..
if the points are not properly adjusted.. you won't get a spark..
if there is an issue on the positive side of the coil there will not be enough voltage to create a spark..
all is not lost...
a picture to help..
i know there is a better article around someplace..
Posted: 08/23/12 08:11 PM
Check the points and condensor. Replace them if needed...Clean all your connections. Those are usually the first places to start. If you can when your working on any NO START problem try to keep a battery charger on your battery. So you don't run into voltage drops. Once you find your problem disconnect the battery and see how the engine performs.