Igniiton issue.

[Condor1970]

Ok, after sitting for a week, I finally got done with my work on the outdrive, and the tried to run my 1989 3.0L Merc this morning.

This is the problem, but first I have a question.

When I turn to key to power on, but not start, everything is on and getting power. However, should there be 12v at the +/- contacts on the ignition coil itself?

If not, then I assume it comes from the alternator only, which makes sense. I checked continuity of the purple wire all the way from the alternator to the ignition coil, and it is fine. When I start the engine, the volt meter on the dash does jump, indicating the alternator is producing power.

The engine starts when I turn the key, but as soon as I release the start switch to normal on position, the power stops to the coil, and the engine quits immediately.

Any suggestions as to where I should start with this?

 

[bruceb58]

Assuming you have points and a ballast wire, you should have 12V at the + side of the coil with the ignition on with points open or around 9V with points closed.

If you have a safety lanyard, it might be disconnected causing this. The reason you get 12V when you crank is because voltage bypasses the resistor wire while cranking. That voltage during cranking comes from the starter solenoid.

 

[Bt Doctur]

sounds like the resistance wire is bad

 

[Condor1970]

No, the system has a Pertronix Electronic upgrade. The resistance wire was cut, and a regular wire installed from the choke to the ignition coil directly.

On a hunch, I decided to check the continuity between the contacts on the Shift interrupter switch.

I am reading a closed circuit between the black and gray wire contacts on the switch, when the switch is centered in the shift interrupter lever.

When I close the switch manually, the contacts stay closed, and there is no change on the ohmmeter.

I assume they are supposed to be "open when centered", then close to ground the ignition system, correct?

 

[bruceb58]

You have to unplug the ESA when making those measurements with an ohm meter. You are basically reading through the ESA circuitry.

If you suspect the ESA for any reason, unplug it and try it. Which ESA is on here? If its the stock ESA, it won't work with a Pertronix unless you do the "diode mod" documented on the Pertronix website.

Curious if the engine has ever been run since this "Upgrade". Not sure on your engine, but some have the choke wired to the AC tap of the alternator.

 

[Bt Doctur]

not knowing how you know how to use the meter makes giving you the correct answer hard. The switch is wired to a plastic block .the top mounting screw also supplies the ground connection .The bottom connection goes to the neg side of the coil.The switch is "normally open" and closes when moved out of the notch to ground the ign system.

 

[Condor1970]

Ok.

The Pertronix system is installed properly. The engine perfectly the last time it ran a week ago, and the ignition system is working as it should.

The problem, is that when I release the start switch from start to the on position, voltage to the ignition coil drops to Zero.

I removed the Interrupt switch, and tested it. The interrupt switch is working fine.

I am measuring continuity between the wires that go "to" the terminal block in front of the interrupt switch. The one wire is white/green, the other is black.

The white/green wire goes to the ignition coil, the black is a ground wire.

Shouldn't there be infinite resistance between the white/green and black wires, when the start switch is in the on position?

 

[bruceb58]

For some reason, I thought you were in the OMC forum so What I said about ESA does not apply to you. My apologies. To test the switch, you need to remove one of the wires off the switch before you do your continuity test.

 

[Condor1970]

I removed the switch completely, and it works perfectly fine. However, I am measuring continuity between the green/white wire and the black ground wire that goes to the switch. As far as I know, there should be no continuity between these 2 wires. That's what grounds the system out.

The white/green wire goes to the gray wire that connects to the ignition coil. The only other component that attaches to that gray wire is the tachometer.

My tachometer is reading 600rpm when the engine is not running. So, I disconnected the tachometer to see if there is any change. There is not.

I reconnected the tachometer and tried to run the engine again, and it still won't run, even when the tach was disconnected, it won't run. The tach does track up when the engine starts, but drops back to and stays at 600rpm when I shut it off.

Now, the tach is reading 700rpm, even when the engine isn't running. It must be getting some voltage from the ignition coil somehow.

I also disconnected the negative battery terminal, and I am still reading continuity between the Interrupt switch wires. As far as I know, they should have infinite resistance.

Does anyone know if these 2 wires are supposed to have continuity or not?

 

[Condor1970]

Moderators,

Can you move this thread to Electrical forum?

Maybe there's someone in there who can help?

 

[bruceb58]

You will get continuity. It is not a valid test.

As far as the tach is concerned, that is also totally normal. When you turn the ignition off, the needle may stop at any position.

Are you powering everything up consistant with Figure 3 of this diagram?
http://pertronix.com/support/manuals...itor12vneg.pdf

Seems like you need the ballast resistor still.

Who installed the Pertronix module?

 

[glenn property of pam]

if the shift switch is bad then the engine will never start or will not drop rpm as its being shifted. in neutral is mean to be open. In gear its meant to be open. Just as the shifter starts to move its meant to be closed. so with a ohm meter connected to switch only (disconnect the wires) you should read high ohms and just as you move lever you should read low ohms. High is over 1k ohm (fancy meters will go all the way to meg ohms so don't expect infinity as they are well to sensitive).

The engine starts so I would ignore the shift switch. What you seem to have is a problem with 12v at the coil when the key is turned to the run position. Keep the meter in volt mode and test if you have voltage at the coil + when the key is turned to run. If not chase that back (ignore ohms readings) with the volt meter to find out where the 12v feed is being lost. If you have a lanyard switch check that as it could work either way (cutting 12v to the coil or shorting the coil - side to ground).
Purple wire is a feed to the alternator (tells alternator engine is running) not from the alternator to the ignition so ignore the alternator this is simply 12v to key common back to 12v on the purple when key is in run position.

 

[glenn property of pam]

You will get continuity. It is not a valid test.

As far as the tach is concerned, that is also totally normal. When you turn the ignition off, the needle may stop at any position.

Are you powering everything up consistant with Figure 3 of this diagram?
http://pertronix.com/support/manuals...itor12vneg.pdf

Seems like you need the ballast resistor still.

Who installed the Pertronix module?

that's what I though. The resistor is added or removed based on the coil. If the coil has a internal resistor then you can remove the external but if the coil was not changed then the external one should still be used.

 

[bruceb58]

I have a feeling whoever installed the Pertronix failed miserably!

 

[Condor1970]

PROBLEM SOLVED!!!!!!

For some reason I wasn't getting any voltage at the ignition coil either, when the key was in the "on" position. It should be getting 12v all the time, not just when the starter is starting the engine.

What was happening, is the coil was getting voltage when the starter was starting the engine, but as soon as it let off the ignition switch, it would quit immediately.

I finally figured out, that on the drawing, the Purple wire that goes all the way from the ignition switch to the coil was not as it should be. Turns out, the connection for the "Pin 2" on the main wire harness connector on the engine must have some corrosion or a little loose. I cut off the tie-wrap, and I can't seem to get it unplugged. It must need the Hulk to pull this thing off.

How do I get this connector apart without killing myself or the boat? I'd like to take it apart and clean them out really good.

Anyway, I decided to just jiggle it around really good, and found the voltage on the coil had returned, and is now staying on. I'm guessing it must have been a little corrosion on the pins. I think running the engine and the vibration may help over time.

As soon as I turned the key, it fired right up, and idled beautifully, runs great.

P.S. I installed the Pertronix. It ran great a week ago, so no reason for that to be the problem. I refuse to fail miserably. . LOL!!!!

 

[glenn property of pam]

when you installed the pertroix did you also change out the coil. There are 2 types of coils. One is a external resistor the other is internal. I would suggest getting a internal resistor type if you have already removed the external resistor wire. Running with out the resistor will lead to the coil burning out when the alternator starts to charger the battery at a higher voltage. As for the connector, If you post a pic we maybe able to work out how it unplugs. Theres so many different designs but generally theres something like a catch to push or lift to unlock the 2 pieces.

p.s glad you got it running

 

[Condor1970]

I got the oil filled 0.6ohm Flame Thrower II, which you can run power straight from 12v, without a resistor wire.

The connector is a large round white rubber connector, that does not appear to have any catches or latches to hold it on. Only a zip-tie was used around the base of it to lock it on, and keep it from sliding off.

 

[bruceb58]

Just a suggestion, next time specify all you have done before posting questions. Kinda slows down troubleshooting when it takes 17 posts to find out what coil you installed.