1987 mercruiser won't shut off

[johnf]

While accelerating to pull a skier, the engine starting making a high pitched noise. I turned the key off, but the engine continued to run (about 1 minute) before I stopped it by disconnecting the negative wires on the battery.

Reconnecting the battery caused arcing. The starter slave solenoid was closed. Replaced the key switch (it was giving problems), the starter slave solenoid and starter.

The engine will crank if I jump from the battery positive to the small yellow-red post on the starter slave solenoid. It will also crank if I disconnect the purple wire from the key switch and turn the key to the "start" position.

With all wires connected to the key switch turning the key to "on" the gauges work, but turning the key to "start" there is no "click" of the solenoid and no crank.

Suggestions?

 

[Dunaruna]

Re: 1987 mercruiser won't shut off

[colour=blue]Hi John, welcome to iboats!!

To help you diagnose the problem, a little background is in order.

What (exactly) was the problem with the ignition switch?

Before you replaced the switch, did it crank o/k?

My initial thoughts are - you have the ignition switch wired incorrectly or a faulty connection.

 

[johnf]

Re: 1987 mercruiser won't shut off

[colour=blue]Hi John, welcome to iboats!!

To help you diagnose the problem, a little background is in order.

What (exactly) was the problem with the ignition switch?

Before you replaced the switch, did it crank o/k?

My initial thoughts are - you have the ignition switch wired incorrectly or a faulty connection.

 

[johnf]

Re: 1987 mercruiser won't shut off

[colour=blue]Hi John, welcome to iboats!!

To help you diagnose the problem, a little background is in order.

What (exactly) was the problem with the ignition switch?

Old ignition switch would "stick" in "start" position and manually need to be turned to "on" position.

Before you replaced the switch, did it crank o/k?

No. After the "high pitched noise" incident the slave solenoid was closed. Reconnecting the battery caused it to arc. Replaced the switch, slave solenoid and starter.

My initial thoughts are - you have the ignition switch wired incorrectly or a faulty connection.

Labeled the leads on the key switch before disconnecting and installing new switch.

 

[johnf]

Re: 1987 mercruiser won't shut off

Purple wire is on the I terminal of the key switch.

 

[Laddies]

Re: 1987 mercruiser won't shut off

It sounds like the unit has a starter solinoid that is shorted out causing the problem

 

[johnf]

Re: 1987 mercruiser won't shut off

I think the starter solenoid is OK because -

The engine will crank if I jump from the battery positive to the small yellow-red post on the starter slave solenoid. It will also crank if I disconnect the purple wire from the key switch and turn the key to the "start" position.

 

[Don S]

Re: 1987 mercruiser won't shut off

Replace the alternator. It was damaged when you removed the battery cable to shut off the engine. It now feeds the ignition through the sense wire.
Next time you have an engine that won't shut down, remove the coil wire. There may be a better way, but you didn't mention which 87 Mercruise you have, 4,6 or 8 cyl.

 

[johnf]

Re: 1987 mercruiser won't shut off

The Mercruiser is a 4 cyl.
I

 

[johnf]

Re: 1987 mercruiser won't shut off

Don S.,
Is it possible to test if the alternator is the problem by disconnecting it?