Looking for advice (possible ignition issue)

[Wisakedjack]

Sprint time engine failed to start. After checking on the usual suspect I've found that the spark between coil lead from the distributor cap and the cylinder head was very weak. It was yellowish and I had to almost touch the head with the lead. My engine has EI module and 3 Ohm Petronix Flamethrower coil connected via a ballast resistor. I've done the following tests:

1. Checked voltage between coil contacts with ignition on: ~7V (which I understand is way low).

2. Removed ballast resistor. Now voltage between coil contacts is 10.6V, but the spark is still weak. When I cranked the engine voltage between coil contacts dropped to 5.5V(!!!).

3. Check coil resistance, which measured ~3.5 Ohm.

4. Replaced coil with a spare one (though I have no idea if it was good). Coil resistance is also about 3.5 Ohm, but no good spark.

5. Put original coil in and connected jumper wire between '+' coil terminal and battery cable on the starter solenoid. Wire from the ignition switch was disconnected. Still no good spark.

I would appreciate any advise on what else I could test or what is possibly wrong here. Can the coil be bad even if its resistance looks right? Its possible that both coils gone bad, but I kinda doubt it. Does it look like an issue with EI module?

Thank you in advance for any help and suggestions.

[JOHN COOKSON]

Are you sure the battery is fully charged and still good? What does the engine sound like when you crank it? Like a weak battery? Give us a voltage reading at the battery when you crank the engine.
Take the voltage readings to ground not the other coil terminal. Coil - is not a ground.
You can get the EI out of the picture temporally by disconnecting the wire from coil - inside the distributor and with the key on and the EI closed touch\remove it to ground while holding the lead from the center of the coil near ground (the engine) This will mimic the circuit make\break action of the EI. Keep at it until you get a decent spark from the coil.
Others will be along. More as I think of it.

TRUE GRIT

[Wisakedjack]

John, I think the battery is ok. I measured 12.3V on the terminals (I have a bank of two). They were charged before I put them back on the boat. The engine sounds ok when I crank it. Definitely not like the weak battery. I will try other things that you've suggested when I get back to the boat this weekend. Thanks for your suggestions.

[hanleyclifford]

Originally Posted by Wisakedjack

John, I think the battery is ok. I measured 12.3V on the terminals (I have a bank of two). They were charged before I put them back on the boat. The engine sounds ok when I crank it. Definitely not like the weak battery. I will try other things that you've suggested when I get back to the boat this weekend. Thanks for your suggestions.

12.3 volts is not a charged battery. A charged battery at rest should show around 12.7 While cranking you should be showing around 10 volts.

[Wisakedjack]

I agree that 12.3V is not a fully charged battery, but it should be enough to turn the engine and produce strong spark. No? Or do you think my spark issues can just be caused by battery being somewhat low on charge? Thanks.

[hanleyclifford]

Originally Posted by Wisakedjack

I agree that 12.3V is not a fully charged battery, but it should be enough to turn the engine and produce strong spark. No? Or do you think my spark issues can just be caused by battery being somewhat low on charge? Thanks.

The really important thing is voltage at coil+ during cranking. Below 9 volts the engine will not fire, though a weak spark may be observed. You may have a lot of resistance in the system which precludes starting with a battery at 12.3 volts. Try connecting your voltmeter red to coil positive and black to the engine block. Crank and observe the voltage.

[romantic comedy]

Take off the wire from the negative terminal of the coil

Hook up a 1 foot, or longer, wire with a bare end to the negative terminal of the coil.

Take the wire from the coil to the cap and pull it out from the cap. You will need to hold it 1/8 to 1/4 inch away from the block to check for spark.

turn on the ignition switch.

Take the wire from the negative of the coil and strike it the the engine block. Hold the coil center wire to check for spark.

You should get a good spark doing this.
--------
it sounds like you are not getting enough voltage to the coil. Maybe bad connections or a bad battery.

[ndutton]

I want to reinforce what others have said and add a comment of my own.

1. DO NOT attempt to measure voltage between the two small posts on the coil. Voltage is measured with the ignition on between the small coil + post and a good engine ground. Try and avoid painted surfaces for the ground point.
2. While you may think the batteries are good, your measured voltage suggests otherwise (like 30% SOC) and during cranking it will be dramatically lower. You should measure the coil input voltage again as described above during cranking for a meaningful number.
3. When was the last time your spark plug wires were replaced? If it has been a while they're probably due anyway and there's no downside in having new wires. After all, they deliver whatever spark you're producing so why not have the best delivery system you can?

Note to Admin:
I propose adding SOC - State of Charge - to the glossary.

[hanleyclifford]

Originally Posted by ndutton

I want to reinforce what others have said and add a comment of my own.

1. DO NOT attempt to measure voltage between the two small posts on the coil. Voltage is measured with the ignition on between the small coil + post and a good engine ground. Try and avoid painted surfaces for the ground point.
2. While you may think the batteries are good, your measured voltage suggests otherwise (like 30% SOC) and during cranking it will be dramatically lower. You should measure the coil input voltage again as described above during cranking for a meaningful number.
3. When was the last time your spark plug wires were replaced? If it has been a while they're probably due anyway and there's no downside in having new wires. After all, they deliver whatever spark you're producing so why not have the best delivery system you can?

Note to Admin:
I propose adding SOC - State of Charge - to the glossary.

Second the motion, with the proviso that SOC be defined as measurement taken 20 minutes after all chargers and loads have been disconnected.

[JOHN COOKSON]

Originally Posted by ndutton

While you may think the batteries are good, your measured voltage suggests otherwise (like 30% SOC) and during cranking it will be dramatically lower. You should measure the coil input voltage again as described above during cranking for a meaningful number.
.

If a pond (battery) holds X gallons of water (electricity) and is full it is at it's full capacity.
If the pond unknowingly silts in it and the capacity is reduced will still appear to be full. If a voltage measurement is taken on a failing battery it may appear to be OK even though the total electrical storage capacity is reduced.
Stress testing the battery will reveal this condition.
My advice to the OP is to:
(A) With the key in the ON position measure the voltage at coil + before the resistor. This will check the wiring, switch and so on before the coil.
(B) Then, as noted, check the voltage at coil + while cranking the engine.
Don't do anything further to the ignition system until you can get satisfactory voltages as noted above.

TRUE GRIT

[Wisakedjack]

Thanks to you all for the suggestions. I am going back to the boat this weekend and will report my findings.

[hanleyclifford]

what is going on with a battery, this is the correct tool to own - available at your local auto boutique:

[Administrator]

Note to Admin:
I propose adding SOC - State of Charge - to the glossary.

Done.

Bill

[romantic comedy]

Hanley, that is a great tool. I have almost that exact one. This week my wife's civic sounded a bit slow when starting. I got out the meter and checked the battery. The voltage was fine but it failed the load test.

Got a new battery right away.

[hanleyclifford]

Originally Posted by romantic comedy

Hanley, that is a great tool. I have almost that exact one. This week my wife's civic sounded a bit slow when starting. I got out the meter and checked the battery. The voltage was fine but it failed the load test.

Got a new battery right away.

Good item for cruisers to carry in the inventory. Batteries are cheap along the ICW - except when they are delivered to a lonely anchorage.

[Wisakedjack]

So, I went back to the boat today and rechecked voltages as was suggested. I got the following readings:

battery voltage: 12.2 V
coil '+' terminal: 11.3 V and 9.3 V while cranking

I also got the battery tester that Hanley suggested and the battery was good(!). I then fully charged the batteries and my readings got better (I did wait about 20 min after charging was complete):

battery voltage: 12.8 V
coil '+' terminal: 11.9 V and 9.9 V while cranking

But I still have the same problem. The spark from the coil lead is still weak. I see some when I hold it really close to the cylinder head (probably less than 1/8").

So, I think the battery is good and can be ruled out. Wires were replaced by the previous owner about 3 years ago. That leaves coil and EI module as possible suspects. Right? What shall I try to test next? Any advise would be greatly appreciated.

[hanleyclifford]

If you are delivering 9.9 Volts to coil + while cranking and are only seeing a weak yellow spark then the coil has to be the next suspect. If you are unsure of the coils you have in inventory maybe this is a good time to acquire one of the coils from the Moyer catalogue. Protect it with that resistor and run a bypass from the "R" terminal on your late starter.

[Wisakedjack]

Thanks Hanley for advise. I should get my new coil today or tomorrow and will report whether that fixes my issue. I went through the epic ('War and Piece' like) thread on the coils and I have one more question. There was a post linking Petronix wiring diagram on whether to connect EI module before or after the ballast resistor. Few replies indicated that people still prefer to connect EI red wire to coil '+' terminal after(!) the ballast. Is there some consensus now on what is the best practice in this regard? Thanks.

[hanleyclifford]

Originally Posted by Wisakedjack

Thanks Hanley for advise. I should get my new coil today or tomorrow and will report whether that fixes my issue. I went through the epic ('War and Piece' like) thread on the coils and I have one more question. There was a post linking Petronix wiring diagram on whether to connect EI module before or after the ballast resistor. Few replies indicated that people still prefer to connect EI red wire to coil '+' terminal after(!) the ballast. Is there some consensus now on what is the best practice in this regard? Thanks.

I'm not real good at consensus but IMO the resistor should be connected before coil+. It is the coil that needs to be protected from excessive voltage (and amperage); the EI is only a switch. You are a good soldier for wading thru that "coilmire". After installation check voltage at coil+ to be sure it is less than 12 volts. Fair winds and tide for a cool coil.

[Wisakedjack]

Hanley, thanks for the advise. Makes sense to me.

[Wisakedjack]

Hanley your suggestion was right on the money. I put a new coil in today and got a good strong spark right away. The engine started right away without needing starter fluid (which I had to use most of the time last season). Many thanks again for everyone's help.

I still need to add ballast resistor and run a wire from 'R' terminal on the starter to '+' coil terminal. I was looking at the starter today and was not sure which one is the terminal 'R'. I am attaching a picture.



Obviously the big terminal is for battery '+' connection. White wire on the right/bottom of the picture is coming from the ignition switch. Which leaves terminal on the upper left section of the starter. Is this terminal 'R'?

[hanleyclifford]

In your picture the "R" terminal is the one with the blue insulator. But there is already a wire there - where does it go now? Maybe the system was or is wired for the bypass. If that wire with the blue insulator goes to coil+ then you are already set. Don't run too much without that resistor and confirm voltage at coil+ once it is installed.

[Wisakedjack]

Thank you for confirming. That wire blue insulation connects 'R' terminal with 'Start Isolation' terminal on the charging relay. So, its basically tells the relay that the starter is cranking. New resistor is on the way. The old one was measuring 2.5Ohm, which is way too much. I am launching the boat this weekend, so I only need to motor to my mooring

[hanleyclifford]

Originally Posted by Wisakedjack

Thank you for confirming. That wire blue insulation connects 'R' terminal with 'Start Isolation' terminal on the charging relay. So, its basically tells the relay that the starter is cranking. New resistor is on the way. The old one was measuring 2.5Ohm, which is way too much. I am launching the boat this weekend, so I only need to motor to my mooring

Understood, but I'm curious - what does the relay do regarding the ignition circuit? 2.5 ohm does sound a bit high - I think mine is around 2.0 - but every boat is a little different and the important thing is voltage at coil +, hot and running with system at equilibrium. My view is that number should not exceed 12 volts, but there are other views out there and it is for you to decide.

[Wisakedjack]

Here is what Blue Systems charging relay manual says about 'Start Isolation':

Start Isolation allows temporary isolation of House loads from Engine circuit during engine cranking to protect sensitive electronics from sags and spikes.

Its an optional feature.

I am planing to play with the couple of resistors to find optimal mode, but in general I agree that coil voltage should be less than 12V.