12 volt issues

[Vip185]

2005 VIP v6 mercruiser. Motor runs good but quits sometimes then wont start. Notice the voltage at the ignition switch reading 3 volts when switching to on. Switch was changed a couple years back. Looking at changing the 90 ohm fuse at the starter. attached is a picture. Its fine right now as i was messing with the wiring at the blower motor switch then had 12.5 volts. Probably just a coincidence. A wiring diagram would be helpful and any suggestions.

 

[Bondo]

Ayuh,.... Welcome Aboard,.... Start by cleanin' to shiny metal Clean both battery cables on both ends,......

 

[mike_i]

If you're measuring the resistance of a fuse as 90 ohms you have issues, it should measure 0. How did you "Notice the voltage at the ignition switch reading 3 volt"? If you measured 3 volts you have an issue. If as you say " Its fine right now as i was messing with the wiring at the blower motor switch then had 12.5 volts" you have issues.

 

[Scott Danforth]

and by shiny metal, we mean polished like your mother-in-laws fine silverware.

use 150 grit sand paper, a wire brush on the end of a drill or similar to get the metal shiny

once done and tight, seal the connections with marine electrical varnish

 

[Vip185]

mike I had a fluke connected to the power wire on the ignition switch. 12.5 volts when key off. When I had the issue it showed 3 volts when turning to on. Of course it wouldn’t start. Can it be the 90 amp fuse by the starter? Its an intermittent 12 volt problem that’s gonna be hard to find.

 

[mike_i]

mike I had a fluke connected to the power wire on the ignition switch. 12.5 volts when key off. When I had the issue it showed 3 volts when turning to on. Of course it wouldn’t start. Can it be the 90 amp fuse by the starter? Its an intermittent 12 volt problem that’s gonna be hard to find.

 

[mike_i]

Not the fuse, it's either good or bad. Did you measure the 12 vdc at the ignition switch on the hot side or the switched side? Where did you measured the 3 volts at? Your statement "Its fine right now as i was messing with the wiring at the blower motor switch then had 12.5 volts" tells me you have a bad/corroded connection somewhere. If you're able to "fix" it by messing with the wires it ain't fixed.

 

[Vip185]

Hot side switch. Where does the positive red wire come from? Have to trace it back hopefully it doesnt go into a connector. Gonna get out there tomorrow. There are two multi wire connectors under the dash where I was moving the blower wires………

 

[Scott Danforth]

Hot side switch. Where does the positive red wire come from? Have to trace it back hopefully it doesnt go into a connector. Gonna get out there tomorrow. There are two multi wire connectors under the dash where I was moving the blower wires………

from the ignition switch working backwards.

ignition switch.......harness connector near the controls/dash...... harness connector at the motor (big round connector)......battery terminal on engine at starter...... battery

dont forget the ground path

 

[Vip185]

I’ll let you know what I find. I got a game plan, thanks

 

[Vip185]

Checked three connectors under the dash looked good. Went to the 90 amp fuse on the starter. The battery cable, fuse and starter post was rusty looking.
Cleaned up with wire brush and emery board used for finger nails. The fuse
And post look to be brass. Looking at engine connector. Got the clamp off. Is it supposed to pull straight off?

 

[Bondo]

Checked three connectors under the dash looked good. Went to the 90 amp fuse on the starter. The battery cable, fuse and starter post was rusty looking.
Cleaned up with wire brush and emery board used for finger nails. The fuse
And post look to be brass. Looking at engine connector. Got the clamp off. Is it supposed to pull straight off?

Ayuh,..... It takes some wigglin', but ya, it pulls straight out,....

 

[Vip185]

Mike I found some corrosion on the engine plug pin 4 had green stuff the rest had a little coating of white stuff. Cleaned it up spread the pins a little put it back together. Ran it on and off for most the afternoon, no problems. Gonna change the ground cable and the positive cable running to the starter. The cable ends look pretty bad. I winterized it and won’t take it out till next year. Thanks for the help everyone.

 

[mike_i]

Hopefully that was your issue and it's fixed. I'd check all the connectors you can get to and clean where necessary and spray some cleaner before reconnecting.

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