TOPIC: 1977 1150 Random Electrical Shutting Off Issue

My 1977 1150 will suddenly shut off while under way. By shut off I mean like the key is turned off. No warning, no sputtering, nothing. Just dies. It is totally random and has happened at various speeds. It always starts right back up. Sometime it does not shut off at all. Sometime it will happen a few times in a short period and not the rest of the day.

For information I installed a new internal and external wiring harness and new rectifier last winter hoping it would cure it but it didn't.

The motor runs great with the exception of the above.

Any ideas? Is my trigger getting ready to go out?

Thanks,

Kevin

Since you have a new internal & external harness installed, my guess would be that one of the (3) wires between the trigger & the switch box is failing.

Be sure and do the following tests separately, so you will know which test identifies the failure.

With the motor running at idle, wiggle and pull lightly on each of these wires, both at the connection to the switch box, and where they enter the trigger. There is a brown wire, black wire, & white wire.
If this doesn't identify the problem, try wiggling the ignition switch while idling, and see if this causes the failure.

If these tests don't isolate the issue, dis-connect the Mercury safety shut-off switch from the brown wire circuit, and lake test.

Please keep us informed.
doc F

If the problem seems to be the neutral safety switch, take the switch out and test it. It may not be the switch. The shifting mechanism that activates (or deactivates ) the switch may be slightly out of adjustment. I had that problem about 5 or 6 years ago.

neutral safety switch wont shut the motor off. it will keep the starter from working only.

Not clear if you tried to fix problem by rewire and it didn't fix it or if problem showed up after rewire.
I suspect your ignition switch itself. There are rotary contacts inside the switch itself. I had a switch go flakey on me.....a brand new one after a few years.
Switch contacts can go bad and secondly switches can be damaged by way overheating the terminal lugs when doing the soldering. So either way if switch was replaced or not it's a likely suspect.
On my situation it was cutting on and off the 12 switched volts to the switch box. The problem was random yet would happen with pretty good frequecy. In addition to cutting out while underway, I could also rely on a few cut outs while cranking. Motor ran in "start" but when you let go and key rotated to "run" it would stop cold.
My guess is either the constant hot 12 volt inside rotary terminal is flakey, which if your choke works when motor conks out then that's OK or the rotary terminal on the switched 12 volt terminal that connects to the switch box is flakey. Either way, switch is not repairable so a new one is in order.
On mine if I rotated the key a few times, quickly the issue would go away....for a while.
At the switch box l probed for power at time of issue and I simply jumped the constant 12 to the switched 12 when problem occured and that fixed it and further it never happened while jumped this way although this keeps motor running till you remove the jumper, still it proved the switch was bad. I put a new switch in and no issues now years later after doing so.
Just a guess....
Randy

doc F,

Thank you for the reply. The Mercury safety cut off switch has been removed so I know that's not it.

Question regarding wiggling the trigger wires. Do I need to worry about getting the crap shocked out of me?

Thanks again,
Kevin

No. 12 V will give you a good tingle, but still it's best not to handle bare wires. Use needle nose pliers with insulated handles.

Thanks for the information. I will report back.

Kevin

Sounds to me like the ignition switch is kaput.

gfgarland wrote:

Sounds to me like the ignition switch is kaput.

I'll second that..seen it

Doc F,

I finally had time to pull the boat out and do the tests you mentioned.

1. With the motor idling I wiggled and pulled on each of the wires running between the trigger and switch box. No Issues.

2. With motor idling I wiggled the ignition switch. No Issues.

3. Mercury switch is not installed in motor.

Will the trigger act up before it totally goes out? If so should I go ahead and replace it?

Thanks,
Kevin