Electrical issues - power where it shouldnt be...I think

A4x4junky

Cadet
Joined
Oct 26, 2017
Messages
6
Hi everyone,

Sorry for the vague title...wasn't even sure what to put.
A little backstory so some of the ... nonsense later might make a little more sense.

I purchased a 97 Bayliner Capri 2050 and trailer last year for almost nothing.
Boat was complete minus engine and outdrive.
The previous owner grenaded the 350 and changed to an import 6 cylinder turbo.
Part of their process was to cut the engine wire harness leaving me about 4" of wire at the connector to work with, move the exhaust mounted controls off the engine, bypass the starter safety switch and...???
Before selling to me the import parts are gone...but so are a lot of the 350 parts.

I purchased another boat (boat was in horrible shape) with good 5.7 and outdrive.
I stripped everything engine and outdrive related including most of the wiring.

I resealed the engine, got that installed and aligned.
Hooked up enough of the engine to jump the starter and got it to run.
Found a diagram of the boat side wiring and rewired the engine side of the connector based on that.

I plugged in the connector and started testing different wires with only power and ground hooked to the engine.
Ignition wire 0 v with key off and 12 v with key on...good.
Start wire 0 v with key off, .6 v with key on, and only 12 v when turned to start. Not sure where the .6 v comes from?
Oil pressure and temperature wires 0 v with key off, but ~6 v with key on. Is this normal?
Alarm wire reading 0 v with key off, 12 v with key on...I assumed this would receive power from the bilge pump?

I hooked up the start wire (wanted to hear the engine turn over from key) and when I try to crank, nothing.
Unlike above (with wires not connected to starter) the volt meter now shows only 5.5 v at the start (trigger) wire.

I bypassed the wire (ran new wire from ignition switch to starter) and the engine cranks with key.

So, somewhere it appears like there is a short or ground or...I dont know.

I know this is a mess, but am hoping someone can help point me in the right direction.

Thanks,
Anthony
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,583
You do have a mess and from what I'm reading your going to need to ring out the harness. These should give you the basics for something with Thunderbolt ignition. If your ignition is different let us know

Merc Color Codes.png

50 57 TB ign.jpg
 

A4x4junky

Cadet
Joined
Oct 26, 2017
Messages
6
Thanks for the response...this is the harness pic that I couldnt find.
I did find the boat side.

Can someone explain the purpose of the starter slave solenoid when the starter already has a solenoid on it?

Also, is it normal that (when not hooked up to the engine) the oil pressure and water temperature sensors have voltage going to them?

This isnt the same ignition system I have (though it might have been right for the boat I have).
I have an older points style distributor.
Does anyone know what resistor I am supposed to run in the + feed to the coil?

This has given me a few things to look at.
Thanks,
Anthony
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,583
T
Can someone explain the purpose of the starter slave solenoid when the starter already has a solenoid on it?

The starter solenoid needs more current to engage, and while the key alone can energize the solenoid, it uses much less current using another relay up close. The key energizes the slave relay, then it does the starter solenoid

Also, is it normal that (when not hooked up to the engine) the oil pressure and water temperature sensors have voltage going to them?

No, they should have no voltage if the key is not ON

This isnt the same ignition system I have (though it might have been right for the boat I have).
I have an older points style distributor.
Does anyone know what resistor I am supposed to run in the + feed to the coil?

You will need a coil which is marked "use externl resistor" then search for "external ballast resistor" and several will show up. Will then need to wire it in as indicated from purple wire to coil.

898.jpg

What you might want to do instead is change out the points for electronic, either Delco EST or Petronics
 

A4x4junky

Cadet
Joined
Oct 26, 2017
Messages
6
Thanks for the help.

I did find my issue.
I was running the start wire directly from the ignition switch to the starter (bypassing the slave solenoid).
Once I wired it like the diagram above (the right way :facepalm: ) it works perfectly.

I found another distributor I would like to use (HEI).
Simple to wire and no points...but I have concerns about the distributor gear.

I will post in the engine section if preferred, but was hoping someone here might be able to help me figure this out.
How would I be able to figure out gear material compatibility?

Thanks,
Anthony
 
Top