Coil question
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From: Riverview, FL
Coil question
I just started to work on my 77 f150 with a 300. I am trying to get it started right now. It is getting fuel but no spark. I think the coil is bad even though it is brand new (previous owner put it on). I checked the 2 wires that hook to it and they both lit up my light tester. Is that supposed to happen? Also when I took both wires off and tested them the pos lit up and the neg didn't, the thing is the key was turned off but it still had power!!! Is that supposed to happen?
Thanks, Andy
Thanks, Andy
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From: Virginia
Hook the wires back up to the coil.
For the following tests always put your negative test lead on the engine block.
With the key off, put the test probe on the coil +. It should read nothing. Turn the key to run. On the + side of the coil, you should read voltage.
Move the probe to the negative or "tach" side of the coil(remember, leave the neg tester probe on the block). While you are holding this on the neg of the coil, get someone to crank the engine. The voltage on the neg of the coil should go up and down when the engine is turning.
If the voltage does not go up and down on the neg of the coil when cranking, then take the top off the distributor, and watch the rotor as you crank the engine. Make sure it's turning. The cam gear on the sixes has a tendency to strip the teeth sometimes.
If the dist is turning, then I would try a new ignition module that is mounted on the fender, or take the module to autozone and let them test it to see if it's good.
For the following tests always put your negative test lead on the engine block.
With the key off, put the test probe on the coil +. It should read nothing. Turn the key to run. On the + side of the coil, you should read voltage.
Move the probe to the negative or "tach" side of the coil(remember, leave the neg tester probe on the block). While you are holding this on the neg of the coil, get someone to crank the engine. The voltage on the neg of the coil should go up and down when the engine is turning.
If the voltage does not go up and down on the neg of the coil when cranking, then take the top off the distributor, and watch the rotor as you crank the engine. Make sure it's turning. The cam gear on the sixes has a tendency to strip the teeth sometimes.
If the dist is turning, then I would try a new ignition module that is mounted on the fender, or take the module to autozone and let them test it to see if it's good.
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