'96 4.3 losing 12vdc in run position

[djtrixx69]

Greetings! Long time lurker, 1st time poster. Boat is a recently aquired '96 Rinker 180 with a 4.3 Merc LX Gen+

I've had it out approximately 10 times since purchase, and every time has started and ran beautifully, just touch the key and away she goes.

We ran up the river to the local swimming hole, and again, she started and ran flawless. Sat and played for a few hours, and when it was time to go, hit the key, fires and dies. When I say this, I mean the engine will fire, as long as the key is all the way in the start position, but when it fires and you let it go to the run position, the engine dies, as if you turned the key all the way off.

I was able to get home by jumping the battery + to coil+, and yes, I had normal oil pressure on the gauge. Ran like a million with the jumper.

I pulled the keyswitch itself, and ohm checked it, no problem there. Every fuse I found was good. I read in a few places that if there's no oil pressure (switch faulty) that it will cut power to the fuel pump. Will this also cut power to the coil? I would think that if the pump gets power it would pump more gas in and would run a bit longer.

Thanks in advance, you guys rock.

 

[Scott Danforth]

get a new key switch. they go bad.

 

[alldodge]

Agree, should be the key
To verify, place ohm meter from common to run, turn key ON. Keep meter probes there and turn to start, then release back to run, continuity should stay connected. Might need to do it a few times for it to break connection

 

[djtrixx69]

Checked the key for 50 cycles, and the key switched is fine. Where else to look?

 

[alldodge]

A bad connection somewhere, and they are hard to find.
Put the key back in and see if you keep getting 12V at the coil. Can remove the small Yellow/Red wire off the slave solenoid so the motor will not crank

Could also shift into gear and the neutral safety switch will keep it from cranking over

 

[Scott Danforth]

if returning the key to run is what kills the motor and bypassing it with a jumper is what keeps it running, something wrong with key switch and how your testing.

replaced two key switches for the same reason over the years. if I wiggled the key just right, the motor would catch before completely dying. replaced the key switch in both instances and all was well.

put a load on the circuit and test the switch. or spend the $18 and replace it.

 

[djtrixx69]

Dumb question, but there should be 12v at the coil + as soon as the key is first turned to run, correct? Before even trying to start?

 

[alldodge]

Dumb question, but there should be 12v at the coil + as soon as the key is first turned to run, correct? Before even trying to start?

Yes

 

[djtrixx69]

Thanks all, I'll test some more tonight.

 

[djtrixx69]

Guys I appreciate the help, in the end it turns out I am just an idiot. After verifying yet again the key switch is ok, and testing wires from the dash to the coil, I happened to look up from under the dash in my best contortionist position, to see that the kill switch on the tether was not in the run position..... Problem solved. Followed by a good two to three hours of heavy drinking and calling myself every name in the book.

Apparently the tether kill just shorts the 12v from the run position and not the start position. Lessons learned.

 

[Scott Danforth]

yes, a kill switch on an outboard with mag ignition grounds the ignition to kill. on an I/O it (and EFI outboards) it simply opens, removing power from the purple wire (ignition)