165 mercrusier

[birsic]

have aproblem burning up coils. I have changed everythig, here is the list:
coil, points, conenser can, cap, rotor, plugs, wires, ground.

someone told me it cold be water in the gear oil of the stern drive causing the whole thing, but I can not really invision that.

could anyone help please

[george allard]

Do you have a ballast resistor before the positive side of the coil or a coil with a built in resistor?

[stonebreaker]

Agree with George - ballast resistor (or lack thereof) could be the problem.

[birsic]

Why yes I have a ballest resister, I have 12V at the battery whit key in on position I get 10.82V at the coil + and 0.28V on the coil -

[wilezcoyote]

I put GM HEI units on my dads 26' commander (twin 165"s)with lock plates on the vac advance, removed the ballest resister wire. faster starts, more power, better on fuel, used units cost @100.oo complete

[kenJ]

I have no boat experience with coils, but on cars they tend to last forever. They have no moving parts, simply a pair of inductive coils seperated by an insulating medium. Only a few things cause failures; input overvoltage - have you checked you alternator output? or something is causing the insulating meduim to break down. If the coil is mounted on the engine try moving to a bulkhead to reduce heat and vibration. If all ready on the bulkhead, try moving it to a cooler area.

[Frosty]

When an engine cranks it takes a lot of power, so much power that there might be little left to energise the ignition system and start the engine. So what they do is have a 9 V coil,--the 12 volts from the ign switch is then reduced to 9 volts to run the 9Vcoil. BUt when cranking with this system there is another wire from the ign swicth that feeds 12 volts directly to the 9V coil momentarily to give the Ignition system a good spark. When the engine starts and you release the Ign switch it goes back to a 12v feed via the balast restor and to the 9 V coil.
What the first 2 guys are saying is you have got the wiring wrong and are feeding the 9v coil 12 Volts all the time.
If this extra wire is broken then this is why engines try to start just as you release the ign switch.
Another thing is you are not leaving the ignition on for any length of time are you?, say for listening to the radio ETC

[gonzo]

Ballast resistors have to be matched to the coil's impedance. Test at the + on the coil for no more than 10V.

[birsic]

all of this has been checked. I recently switched the points out for an electronic pick up.

I still get around 12v not running
I get around 9v running and
with increasedthrottle I get more V the more throttle I give.

The vibration thing that was mentioned is a new one to me and that might be it and is worth moving the coil to find out. so I will be buying a set of longer spark plug wires and moving the coile to an area that is cooler and little to no vibration. where it is at now shakes it like crazy.

[stonebreaker]

Originally Posted by birsic

I get around 9v running and
with increasedthrottle I get more V the more throttle I give.

OK, voltage increasing with rpm sounds like the voltage regulator on the alternator is shot. Sometimes they can be replaced separately, sometimes the whole alternator has to be replaced. If you can remove the alternator from the motor, most auto parts stores will test it for you free.

[gonzo]

Does it still have the alternator in the front pulley? Voltage regulators can always be replaced. They can be internal or external though.

[george allard]

Remove the alternator belt, run the engine, for a morment, and check the voltage. Don't run to long and overheat the engine.

[gonzo]

The original 165 has an alternator under the front pulley. It looks like an outboard one. There is no belt but the wire to it could be disconnected.

[george allard]

My last 165 had a belt driven Delco, You had to remove the front engine mount bolt, and raise the engine to change the belt. Lots of fun.