2004 22V Mercruiser Won't Turn Off With Ignition

[wakeborder5]

I finally got my boat from the guy storing it (he's an idiot -- and i also have a hurt knee and wasn't in a hurry to get it and tempt myself with riding). When I fired it up, I went to turn it back off a moment later and the key did not shut the engine down. I then went to the perko and switched it to off -- still running. Then I went to the ignition and turned the key as if starting the engine -- this caused a quick screetching noise from the starter and then the engine turned off.

I figured it's not the ignition because the gauges turn on/off with the key. My understanding from my research is that the engine didn't turn off as I expected when I turned off the Perko because the alternator feeds the engine when it's running and the batteries aren't needed at that point. Is that true?

I gather that this is an issue with the solenoid not accepting the ignition signal to shut off.

1. Does it seem like this is a solenoid issue?
2. Does anyone have any instructions or the manual for changing this? I have the Mercruiser 350 Mag and am not sure where it's located.
3. Should I check something else before the solenoid? What kind of diagnosis can I do?

Thanks!

[boatwakes]

It's a key switch issue, the internal key switch is not opening the contacts when you turn it off so the coil is still getting power. Replace that and the alternator because you fried the internal diode when you shut the battery switch off with the engine running.

[wakeborder5]

It's a key switch issue, the internal key switch is not opening the contacts when you turn it off so the coil is still getting power. Replace that and the alternator because you fried the internal diode when you shut the battery switch off with the engine running.

I noticed today that I missed one of the negative cables when hooking up the battery that feeds a grounding distribution block for several things under the dash. I don't know if it was that or if something finally came to life after the long, cold winter, but it fired up and turned off without problem this time. Are you sure that I should replace the alternator and that the internal diode was fried? This may be a really dumb question...but is there a way to tell if the alternator is fried?

Thanks for the help

[boatwakes]

The internal diode fails when the battery switch is shut off, while the engine is running, 99% of the time. Take the unit off and have a local shop test it to determine if it's still good and not back feeding power. If your batteries die after a short time of no use, that's also an indication that the diodes crapped out. As for the ground, that should not have made a difference in the on/off for coil power but glad you found it.

[CJAuster]

The internal diode fails when the battery switch is shut off, while the engine is running, 99% of the time. Take the unit off and have a local shop test it to determine if it's still good and not back feeding power. If your batteries die after a short time of no use, that's also an indication that the diodes crapped out. As for the ground, that should not have made a difference in the on/off for coil power but glad you found it.

I changed my battery recently, and am having he exact same issue. Left a cable off and everything. Now it won't shut off after running for a while, drains the battery. Did you hangs the alternator and was that the issue?

[KoolAid]

Still sounds like the ignition switch. Check for power on two or more posts on the back of the ignition switch. Only one should have power when the key is off. two when in the "on" position.

[lee]

.but is there a way to tell if the alternator is fried?

Thanks for the help

Start the boat and check the voltage with a multimeter. You can check voltage at the battery or the alternator.

[chameleonstang]

I had this issue with mine and it ended up being one of the wires on the alterntor that was crimped and had a bad connection.

[CJAuster]

Start the boat and check the voltage with a multimeter. You can check voltage at the battery or the alternator.

Got a new key switch, wire, and sending unit. Shop put it on and said the boat is good. I bring it home, and the next day I try to start it and the battery is low. Yanked the battery and it tested at 11.2 volts.

Seems like something is still draining the power, or the shop didnt charge my battery fully before replacing back in the boat and giving me the ok.

Any suggestions on what to check next? I hear alternator, Im not sure where to place the positive cable on the voltage meter to test if the alternator is drawing the battery power.

Thanks for the help guys.

[CJAuster]

Also, the alternator is tough to get too. Any one have suggestions on how to get to it to remove and put it back on?

[freeheel4life]

CJ, welcome to turning wrenches on boats...Pretty much everything is tough to get to, especially if you aren't a small guy. Patience and work lights help. I would remove your battery first and put it on a two Amp tender and fully charge and test it. Eliminate one variable at a time. If battery is good, put it back in the boat, connect positives, then hook up your multimeter in series between ground post of battery and ground cables in Amp mode and see if you have a key off drain(if you have multiple grounds hooked to battery you will have to check each one in series). If you get an amperage reading of anything more than miliamps you have a key off drain that is pulling down your battery. If you do have a key off drain report back and I can try to help you isolate it with a couple quick tricks.

And Lee is right, check alternator output voltage while running. Should be between 13.6-14.2 volts in a perfect world.