No Spark Mystery

[achris]

I was looking for a spark by putting a lighted spark tester on a wire than hooking the other end on the spark plug. And yes, I have 11.4 volts on the negative side of the coil with all test wires unhooked and points closed. The voltage does not change on the negative terminal whether the points are open or closed.

That says the wire or the points are bad.

The wire that runs from the stud on the points, to the distributor housing, than to the negative side of the coil felt like it was cracking as I bending and feeling it by the dizzy housing where it comes out. Can I replace that wire with another one? It seems like i could put a ring terminal on both ends of a wire and hook it up to from the points to the coil.

Yes. Just be aware that there is likely a grommet on that wire, and to retain SAE-J1171, it needs to have the grommet on it.

Is there another way to test for spark besides a light up spark tester? I have also tried starting and moving the interrupter switch just to verify that is not it.

My usual way to check for spark is to pull the HT lead out of the centre of the dissy cap and put a spark plug in it and lay the spark plug on the top of the engine. That confirms that the coil is making a spark, and takes the rotor and cap out of the equation for the moment. If I get spark form the coil, but not at the plug, I'm chasing an HT problem, not a '12v' problem. Sounds like you're chasing a 12v problem.

Put a new wire between coil - and the points, see how that goes.

Chris.....

 

[andrewterri]

Update, the mystery deepens. Achris, I replaced the wire between the points and coil and was able to retain the wire grommet. I also removed the points and cleaned the base with a towel and wire brush to make sure it has good contact. With doing all of this I still have the same problem. The voltage did drop but only to 10.8 from 11.4 at the positive and negative coil terminals. Just like it was before, the voltage at both terminals did not matter if the points were open or closed.

I also did the spark test you suggested using the HT wire and got nothing. I moved the plug to several spots on the block to ensure a good ground and no spark. So I do not know where in the world the system is not grounding at or why there is no spark. Achris, do you or anyone else have anymore thoughts on where to look next? I have the tac wire and hour meter wire unhooked. Would that affect anything?

 

[achris]

Weird!

Ok, with the points open, and your test plug on the engine block. Get a short length of wire, connect to the coil -. Tap the other end on the engine block (ground). See if you get a spark... If you do (and I suspect you will), next try tapping it on the distributor body... Let us know...

Another thought. If you get a spark on the distributor body tapping, get a wire and connect from any ground to the ground plate of the points, see if that helps.

Chris..........

 

[andrewterri]

I will check that but think I might have already done that yesterday, kind of. When I had the jumper wire on the coil negative and touched it to the distributor plate to check the voltage at the coil + I got a large arc each time it touched the plate. I also got a big arc when the jumper wire went from the - coil to the negative battery post. As soon as the end of the jumper wire got close to the dizzy plate and battery post it got a big arc as it touched.

However, I will follow your steps as noted and report back. Thank you again for your time helping me and others reading this in the future.

 

[andrewterri]

achris, are you talking about using a spark plug in the HT lead from the coil to the block. Than use the jumper wire from coil - to engine block?

 

[achris]

achris, are you talking about using a spark plug in the HT lead from the coil to the block. Than use the jumper wire from coil - to engine block?

Yes.

 

[andrewterri]

not to put the horse in front of the cart but If I do get spark from the plug against the block like you think what would that mean? That way if I get spark I now what to look for or do next.

 

[Roadblock007]

I have 1991 3.0L and had an intermittent no spark issue I was chasing all over. I blew 2 testers and melted wire leads I made up because the battery was pumping out all kinds of power. My issue was that the shift interrupt at the top of the motor was not in the correct position. Probably not your issue, but your initial problem sounds a lot like what I was dealing with so I figured I'd chime in. Mine doesn't have points ignition btw. I know you said the shift interupt isn't engaged but is it functioning properly?

 

[andrewterri]

Thank you for chiming in. I have wondered that. Do you know if it is the white or black wires that are disconnected to bypass it? How did you test/figure it out?

 

[achris]

Thank you for chiming in. I have wondered that. Do you know if it is the white or black wires that are disconnected to bypass it? How did you test/figure it out?

If your interrupt switch was causing the problem, then the voltage on the coil - would be 0 all the time...

 

[andrewterri]

i did the test as you said and I did get a big arch achris. i don't know if it matters but the negative wire from the dizzy was hooked up too. What does the arch to the block from the jumper cable tell you?

 

[achris]

There will be a small spark between the shorting wire and the block, not a 'big arc'. Ok. 3 in every million coils replaced is actually faulty. Have you tried a new coil?

Chris.......

 

[andrewterri]

The arc was not small like a spark plug arc. I have changed the coil just in case and have the same problem with the same symtoms

 

[achris]

PM.