Intermittent ESA in Cobra

[chconger]

Hi

I have just replaced my ESA to find it behaves as the old one. Basically when i manually depress the normally open switch that rides the cam, it does not stumble the engine reliably. It probably stumbles the engine about 10% of the time. I have gone over the wiring and confirmed continuity, confirmed a good solid ground, and confirmed the switches are operational.

I am idling at about 500RPM...tried varying that with no effect.


There is one clue left here;

With the ignition in the "on" position, and the engine not running, the "switched 12V" Violet wire is not coming in to the ESA at 12V. It's reading 10V The battery itself is strong and well above 12V at the terminal posts.

Now I understand that this line goes to the ESA and splits on to the ballast resistor wire and then to the coil primary. And in the condition i am describing (ignition on but not running) there will be current flowing through the primary. But at the point of the ESA input, I should expect 12V there correct? The voltage drops will occur along the ballast wire and the coil itself.

Could it be that I have a something providing resistance upstream towards the key?

Would 10V at the ESA be a problem, or is there an expected drop in V prior to the ballast wire?


Thanks Much
Chris

 

[bruceb58]

Re: Intermittent ESA in Cobra

It should always be between 13 and 14 volts with the engine running. You have a resistive connection somewhere.

 

[chconger]

Re: Intermittent ESA in Cobra

Thanks Bruce. Ill check out the entire path tonight.

Its interesting that the engine still runs fine like this loss. That's why I thought there was a chance this may be "normal". Perhaps I am in for a performance improvement too ;-)

Cheers
Chris

 

[chconger]

Re: Intermittent ESA in Cobra

Update;

Found the lanyard switch (the safety kill switch your supposed to attach to yourself) was adding 5 ohms to the ignition loop from the battery to the ESA / Ballast split. OK! this switch needs be replaced. So I cut it out of the circuit, and joined the wires leading to it.

This gave me 0.6 ohms from the battery plus cable back to the ESA with ignition "on"; the entire loop. Great.

But... it still did not work; bypassing the lanyard did not cure my ailments with the ESA.

Next; I bypassed the entire key switch loop, and ran a short wire from the +12V post at the battery directly to the ESA input. Now the ESA works every time. Hey!!

So the ESA is obviously sensitive to resistance in the switch line....but 0.6 ohms!? Wow.

So my boat is a 1990 Glastron 20'. OMC Cobra 5.0 (Ford). The power goes to the key. Then the violet ignition wire comes off the key and is daisy-chained to every single instrument in the panel, then its off to the lanyard switch, and from there it finally decides to wander back to the stern to see if it can do something with the ESA and coil primary. Yikes..do all boats do this? That seems prone to issues.

I mention this circuit description here because my second experiment was to bypass all this above...but not the key. I ran a wire from the key switch (violet side) direct to the ESA and the result? ....reliable ESA function again.

My plan is to buy some violet wire (so the next guy can figure this out), and power the ESA from the key switch direct, in parallel with the ignition -- which seems to have worked fine with 5 ohms in there.

I am obviously on my way now to fixing this one way or another.

I am just posting this finding as I see a lot of folks frustrated with the ESA...to the point of cutting them out and going "merc". (I was looking at relays and 555 timers myself yesterday) But I have not see a discussion, in this forum or any other, of the sensitivity of the switched +12 volts to the ESA and all that can go wrong with that circuit in an older boat. Its a good thing for folks to verify before replacing an ESA (like me).

In my case...just because you have a great running engine, does not mean you have clean +12V to the ESA. Be aware..the coil does not seem to be bothered.

Hope that helps someone out there one day.

Cheers
Chris

 

[bruceb58]

Re: Intermittent ESA in Cobra

Measuring ohms for a circuit like this is a losing battle since tenths of an ohm are going to cause you problems. Measure voltage drops instead and you will find your answer.

With the engine running measure the following:

1) Battery positive to ignition switch input.
2) Ignition switch input to ignition switch output.
3) Ignition switch output to the input to the supply input to your ESA or ballast wire.

Those voltage drops should be minimal but probably one is going to be high.

From the battery to the ignition switch, you are going through the main engine connector. Likewise form the ignition switch output back to the engine. That engine connector could easily have enough corrosion at the terminals to be your problem.

Also, from the battery to the ignition switch, you also have a connection from the battery at the starter solenoid to the main electrical feed. That is a place for a bad electrical connection as well.

 

[chconger]

Re: Intermittent ESA in Cobra

Thanks again Bruce. Fixing the current wiring is certainly preferable to running a parallel line.

Can you advise Is there a voltage drop that would be acceptable? Anything less than....?

Chris

 

[bruceb58]

Re: Intermittent ESA in Cobra

You are measuring some huge drops so it should be pretty obvious where the offender is. A few tenths of a volt is what you should be seeing.

 

[chconger]

Re: Intermittent ESA in Cobra

Here are some voltage drop measurements.

1) Battery positive to ignition switch input. .049V
2) Ignition switch input to ignition switch output. .064V
3) Ignition switch output to the input to the supply input to your ESA or ballast wire. .124V

Total loss 0.237V

So I am loosing only 237mV from battery to ESA. Yet its proven enough to stop the ESA from working as I bypass from ignition side of the Key to ESA direct, and it works every time.

Is 237mV excessive? Seems like the circuit should expect that kind of variation....

 

[bruceb58]

Re: Intermittent ESA in Cobra

Something isn't right because you measured 10V at the ESA before. There should have been a total of 3V drop.

You are doing all of this with the engine running right?

Try measuring the battery positive post to the ESA.

Your bypass wire has been removed right?

 

[chconger]

Re: Intermittent ESA in Cobra

Hi Bruce

Recall when I measured 10V at the ESA; I found that my lanyard switch was adding 5 ohms. All the measurements I posted below were with the lanyard out of the circuit, and the wires leading to it tied together.

I have since replaced the old lanyard switch with a new one.

All these measurements were made without the "bypass" wire. (and all future ones will)

Now...I apologize as I do see I did not follow one of your instructions properly, and have more work to do. All the measurements below are with the ignition on...but the engine not running. So there is current flowing though the primary coil if I am seeing any drops at all.

Regardless, I will re-do with a running engine.

Thanks
Chris

 

[bruceb58]

Re: Intermittent ESA in Cobra

Now...I apologize as I do see I did not follow one of your instructions properly, and have more work to do. All the measurements below are with the ignition on...but the engine not running. So there is current flowing though the primary coil if I am seeing any drops at all.

Regardless, I will re-do with a running engine.

Thanks
Chris

Well, you don't have to do it with a running engine if you make sure your points are closed. By having it running you do have it in the exact configuration where you have you voltage drop though.

If the points are open, you have no current running through the primary of the coil so you won't have a voltage drop.

 

[chconger]

Re: Intermittent ESA in Cobra

OK, yes I figured as long as the points are closed, then the measurements would be representative.

Regardless, last night i measured on a running motor with;

ESA bypass wire removed
New lanyard switch in circuit

Here are the V drops from positive post on battery;

1) Battery positive to ignition switch input; 0.05V
2) Ignition switch input to ignition switch output; 0.15V
3) Ignition switch output to the input to the supply input to your ESA or ballast wire; 0.34V

So running engine is slightly, but not dramatically, worse at the ESA.

In this condition, the ESA will not work. When I throw in that bypass wire from the ignition side of the key to the ESA, it works.

Looks forward to your opinion.

Thanks
Chris

 

[bruceb58]

Re: Intermittent ESA in Cobra

So what is the voltage at the ESA right now?

How is the ground attachment for your ESA? May want to remove it, clean it, and reinstall it.

 

[chconger]

Re: Intermittent ESA in Cobra

Hi Bruce

I can measure the absolute voltage at the ESA tonight with the engine running. And I will.

But I am not hopeful there will be much to see. It will be 0.34 less than the positive side of the battery; which has the juice to turn over and fire up that old 5L engine in about .2 seconds....with the running light on!

The ESA ground is bright and clean. I cleaned it up as step #1 in my adventure here. As well, one of my experiments was to jumper that ground direct to the negative battery post. No improvement.

The only thing that makes the ESA work so far is to jump over the violet wire to the ignition side of the key, (or closer to the positive side of the battery, but I wont do that as I want it switched)

I think you see my drop of 0.34V as normal in range?

With a brand new lanyard switch in, the only other experiment I can think of, is to move my Jumper wire progressively away from the key, closer to the ESA, perhaps to the ESA side of the panel, and see where the ESA stops working. Or alternatively, run a small jump over the pannel so the ESA and ignition gets a parallel path over the pannel.

Is it common to have the violet ignition wire daisy chain through the instruments?

I should also mention that there is no tinned marine wire in this boat. This craft must pre-date that standard. The only tinned piece is now my jumper.

Cheers
Chris

 

[bruceb58]

Re: Intermittent ESA in Cobra

Very strange indeed.

From your ignition switch, there should be one wire that goes to the safety lanyard switch and another that goes to your gauges.

0.34V seems fine to me.

What is the battery voltage/ESA voltage with the engien running? Maybe your alternator isn't putting out full voltage.

 

[chconger]

Re: Intermittent ESA in Cobra

Ill give those voltages tomorrow (or late tonight). Have to pretend to work now.

I can say that there is only one wire off the ignition side of the key. It goes to each instrument before it goes to the lanyard, from the lanyard it heads to the ESA / ballast split.

Now I can also say that the lanyard, as I found it, shows evidence that it was not installed at the same time as the boat was built. It was crimped in, with different wire (perhaps to import to Canada). As well I found 3 feet of tie-wrapped loops of violet wire associated with these crimps to the lanyard.

Perhaps when the boat was built, there was separate lines to the ESA and instruments, then when the lanyard was added later, the parallel line around the instruments was lost. Who knows...just a guess.

So a thing to do regardless of my ESA problem, as you suggest; is to set up a unique wire for the instruments only, and another wire to the lanyard and on to ESA / Ignition.

Later
Chris

 

[bruceb58]

Re: Intermittent ESA in Cobra

Yes, I would consider doing that.