Mercruiser 3.0 Coil Too Hot Engine cuts out after 30minutes

[lognum]

Correct we are arguing the same point. He should read 0 ohms between the white wire and the battery +. The fact that he was reading 8 volts at the coil with the white wire attached is a concern. Need to know if there is 12 v on the white wire with the key on, when it is not attached to anything. If he has 12 v there then he can go ahead and splice that white wire to the red wire from the electronic ignition module (make sure you have 0 volts with the key off). Then reattach both the y/p wire and the purple resistance wire to the coil +. At that point it should be wired correctly.

Thanks Bruce58 and Stonyloam. If you are both in agreement with the above statement, I will give it a try and report back?

 

[lognum]

Correct we are arguing the same point. He should read 0 ohms between the white wire and the battery +. The fact that he was reading 8 volts at the coil with the white wire attached is a concern. Need to know if there is 12 v on the white wire with the key on, when it is not attached to anything. If he has 12 v there then he can go ahead and splice that white wire to the red wire from the electronic ignition module (make sure you have 0 volts with the key off). Then reattach both the y/p wire and the purple resistance wire to the coil +. At that point it should be wired correctly.

Stonyloam, Can you clarify "splice that white wire to the red wire from the electronic ignition module"? Why would I splice into the positive wire from the EI when they are both on the + post of the coil (see previous pic)?

 

[lognum]

Having the wire disconnected when measuring voltage tells you basically nothing. It's going to measure battery voltage.

2 measurements have been made that contradict each other. He measured basically 0 ohms between the white wire while disconnected and the positive battery post. He measured 8 volts at the coil with the key on. If he really had 0 ohms, he should have measured 12V at the coil.

At this point he needs to follow that white wire and see what it is connected to. He has made as many measurements as he can do and nothing is conclusive.

Bruce, he white wire is connected directly to the key ignition at the helm of the boat.

 

[stonyloam]

You will remove the white wire, and the red electronic module wires from the coil, otherwise you would be getting 12v to the coil from the white white YOU DO NOT WANT THIS. The module DOES NEED 12v, so you will attach the red module wire to the white ignition wire. Your coil needs reduced voltage while running, so you will attach the purple resistance wire to the coil +. Your coil also needs 12v from the starter solenoid WHEN THE STARTER IS TURNING THE ENGINE so you will also attach the purple/ yellow wire to the coil +. So red to white (not attached to coil) and purple and purple/yellow to coil +.

 

[bruceb58]

Bruce, he white wire is connected directly to the key ignition at the helm of the boat.

Yes...no bueno. Stonyloam has a good set of instructions.

 

[lognum]

You will remove the white wire, and the red electronic module wires from the coil, otherwise you would be getting 12v to the coil from the white white YOU DO NOT WANT THIS. The module DOES NEED 12v, so you will attach the red module wire to the white ignition wire. Your coil needs reduced voltage while running, so you will attach the purple resistance wire to the coil +. Your coil also needs 12v from the starter solenoid WHEN THE STARTER IS TURNING THE ENGINE so you will also attach the purple/ yellow wire to the coil +. So red to white (not attached to coil) and purple and purple/yellow to coil +.

Thanks!! Will give it a try and advise.

 

[lognum]

You will remove the white wire, and the red electronic module wires from the coil, otherwise you would be getting 12v to the coil from the white white YOU DO NOT WANT THIS. The module DOES NEED 12v, so you will attach the red module wire to the white ignition wire. Your coil needs reduced voltage while running, so you will attach the purple resistance wire to the coil +. Your coil also needs 12v from the starter solenoid WHEN THE STARTER IS TURNING THE ENGINE so you will also attach the purple/ yellow wire to the coil +. So red to white (not attached to coil) and purple and purple/yellow to coil +.

Stonyloam, One last thing. I called Sierra (just for peace of mind) and they confirmed that the EI needs unresisted voltage. If the coil had an internal resistor, you could keep the red module wire on the + post of the coil, as you know. My question is; your suggestion of attaching the red module wire and the white ignition wire together, does that not give 12volts continuous to the EI? Isn't this the same as leaving the engine on "run" as some have warned not to, or, am I not understanding how it works?

 

[stonyloam]

From your description of what the mechanic did, that white wire should be switched on and off by the ignition switch. You will want to check that. 0 volts with switch off, 12 v with switch on run. The usual procedure is to splice a wire into the purple wire going INTO the electric choke, and attach it to the red module wire, but if you have a good connection on the white wire it should be OK. On a Mercruiser purple wires are switched by the ignition.

 

[lognum]

From your description of what the mechanic did, that white wire should be switched on and off by the ignition switch. You will want to check that. 0 volts with switch off, 12 v with switch on run. The usual procedure is to splice a wire into the purple wire going INTO the electric choke, and attach it to the red module wire, but if you have a good connection on the white wire it should be OK. On a Mercruiser purple wires are switched by the ignition.

Thanks again!! Will report back.

 

[lognum]

Thanks BruceB58 and Stonyloam. All seems to be working fine now, thanks to your input. If you are ever in or near Bobcaygeon Ontario Canada, I owe you a drink........or two Cheers!!

 

[stonyloam]

Thanks, will keep that in mind. Glad it is working well.

 

[corytha]

I am repeating what a few people already mentioned. If you installed a Pertronix, you still need the ballast resistor inline with the coil. The ignitor itself needs to be powered with straight 12v before the resistor.

With the Pertronix in there, measuring the voltage at the plus side of the coil isn't going to tell you much since it will read 12v no matter if a resistor is in there or not.

The best test to see if you have the resistor wire in there, take all the wires off the negative side of the coil, jumper the negative side of the coil to ground and measure the voltage. It should drop to 9V. If it stays at 12V, yo don't have the resistor in there anymore.

Do I do this when motor is running?

 

[corytha]

Thanks BruceB58 and Stonyloam. All seems to be working fine now, thanks to your input. If you are ever in or near Bobcaygeon Ontario Canada, I owe you a drink........or two Cheers!!

Hello, You connected the white to the red direct? bypassing the coil?