1987 Johnston 150GT wont turn off

[Bosunsmate]

So i did the ground out of the power pack Direct and it shut down. So i started to start esting the key to the yellow and black. Key on open circuit motor ran fine. Turned key off closed the circuit. Both sides registered the same so it is grounding out the power packs. But when re connected it still runs on half the cylinders.

ok so both powerpacks seem ok, might be your ground in the control or the wires are of poor quality.
A crap ground can mean only one powerpack grounds out.
Might be the ground to control box pure black wire. Try running a jumper from a good ground on the engine to a good bolt on the control box and try again.
If that doesnt work, hook a wire up to a bolt on the control and then hook it up to a switch that connects to black/yellow on both powerpacks, try that switch does that kill both?

 

[porz0011]

ok so both powerpacks seem ok, might be your ground in the control or the wires are of poor quality.
A crap ground can mean only one powerpack grounds out.
Might be the ground to control box pure black wire. Try running a jumper from a good ground on the engine to a good bolt on the control box and try again.
If that doesnt work, hook a wire up to a bolt on the control and then hook it up to a switch that connects to black/yellow on both powerpacks, try that switch does that kill both?

Where would the control box be located? Or what does it look like?

 

[dwco5051]

I found a wiring diagram I hand wrote many years ago and attached it as a PDF file.

I believe you have one of three possible choices.

No continuity between point A and B. Check plug between yellow/black and yellow/blue wires. Bad diode, it is open. If it was shorted both sides would shut down when shifting.

Power Pack itself on starboard side not properly grounded

Defective power pack. Swap the power packs and see if the port side now continues to run.

View attachment wiring001.pdf

 

[Bosunsmate]

Where would the control box be located? Or what does it look like?

It looks like what you put your hand on to turn the key and move the throttle forward:laugh:
Ive no idea what the diode is for or if its on that motor but its worth checking up on what Dwco says too

 

[dwco5051]

It looks like what you put your hand on to turn the key and move the throttle forward:laugh:
Ive no idea what the diode is for or if its on that motor but its worth checking up on what Dwco says too

The diode keeps both powerpacks from shutting down when the shift swich kills the starboard side. It acts like a check valve so that current will only flow one way. If that is open, not connected, or has a broken wire the ignition switch will not kill that bank. Since the ignition switch kills the left bank the only thing left is from the orange/black wire to the powerpack.

 

[porz0011]

Fixed the issue. The connector to the yellow and blk wire had a broken connection in the boot between the pin and wire. No way to tell. I was checking the resistance and i moved the main wire harness off engine and not the power pack and lost resistance. So i cut out the boot connect and used a male and female flat connector and works great. Thanks for the help.

 

[emdsapmgr]

That's some great electrical troubleshooting!