Wiring a starter motor Johnson 25 hp

J

Jay Jay

Well-Known Member
Joined
29 Mar 2020
Messages
88
Location
Cardiff
Visit site
I seem to be on here a fair bit these day's, firstly can anyone tell me does the negative wire have to be as heavy as the live and also am I wrong to wire it this way, I have the live from the battery to my 2 pin starter button then from the button to the solenoid via a 50 amp fuse ( is this fuse to big ) and from the solenoid to the starter motor, and I have the negative wire from the battery directly to the solenoid then from the solenoid to ground, the reason I am thinking that the negative doesn't need to be as big as the live is because the negative poles on the solenoid are a lot smaller, can anyone please advise. Thanks Jay jay
 
Tell me what model. year and/or model number and I might be able to find a wiring diagram

The negative battery cable must be just as heavy as the positive .... it carries the same current!
 
Last edited:
Also drawing all the cranking current through the start button instead of using the solenoid doesn’t seem right - it certainly wouldn’t be on a normal diesel - but just possibly it’s how things are done on small outboards? I don’t know much about electric-start outboards.

Pete
 
VicS said:
Tell me what model. year and/or model number and I might be able to find a wiring diagram

The negative battery cable must be just as heavy as the positive .... it carries the same current!
Click to expand...
Hi VicS it's John again, I was on here the other day about my starter motor and you showed me the one I needed, I don't know if you read all of the thread but I got a starter motor and now I want to put the outboard it's a Johnson, Model no: 25BA78C You told it's a short shaft version but it has bee converted to a long shaft so would that make it 25BAL78 like you said is a valid number, Oh !! and I have the same gauge negative wire I was only enquiring
 
prv said:
Also drawing all the cranking current through the start button instead of using the solenoid doesn’t seem right - it certainly wouldn’t be on a normal diesel - but just possibly it’s how things are done on small outboards? I don’t know much about electric-start outboards.

Pete
Click to expand...
No it isnt right and that's not how it should be wired.
 
Jay Jay said:
I seem to be on here a fair bit these day's, firstly can anyone tell me does the negative wire have to be as heavy as the live and also am I wrong to wire it this way, I have the live from the battery to my 2 pin starter button then from the button to the solenoid via a 50 amp fuse ( is this fuse to big ) and from the solenoid to the starter motor, and I have the negative wire from the battery directly to the solenoid then from the solenoid to ground, the reason I am thinking that the negative doesn't need to be as big as the live is because the negative poles on the solenoid are a lot smaller, can anyone please advise. Thanks Jay jay
Click to expand...

Outboard starter circuits are very simple, and there is nothing unique about your 25hp Johnson. The thick red wire goes from battery to solenoid and then from the other side of the solenoid to the starter. A thick black wire goes from the starter back to the battery or suitable earth point. Two thin wires then go from the solenoid up to the helm switch (either key or push button). They can have a start in gear switch placed in line. The thick wires are not normally fused.
 
prv said:
Also drawing all the cranking current through the start button instead of using the solenoid doesn’t seem right - it certainly wouldn’t be on a normal diesel - but just possibly it’s how things are done on small outboards? I don’t know much about electric-start outboards.

Pete
Click to expand...

I was hoping it's just a poor verbal explanation! Needs a diagram really to show how the OP has it wired.
 
CLB said:
Outboard starter circuits are very simple, and there is nothing unique about your 25hp Johnson. The thick red wire goes from battery to solenoid and then from the other side of the solenoid to the starter. A thick black wire goes from the starter back to the battery or suitable earth point. Two thin wires then go from the solenoid up to the helm switch (either key or push button). They can have a start in gear switch placed in line. The thick wires are not normally fused.
Click to expand...

Jay Jay said:
Brilliant, that sounds very simple and much easier than how I was going to do it. Many thanks jay Jay
Click to expand...
I don't think you will get far with just those instructions but the diagram below might help

( I realise you may not have a neutral strt switc, in which case the connection from the solenodd goes directly to ground ( negative)

1607372301675.png
 
prv said:
The explanation is perfectly clear, just wrong :)

Pete
Click to expand...

I thought it was lacking enough detail to know!
VicS said:
I don't think you will get far with just those instructions but the diagram below might help

( I realise you may not have a neutral strt switc, in which case the connection from the solenodd goes directly to ground ( negative)

View attachment 104534
Click to expand...

That looks like a "quick sketch" - you haven't shown the earth return off the starter.
 
Jay Jay said:
I seem to be on here a fair bit these day's, firstly can anyone tell me does the negative wire have to be as heavy as the live and also am I wrong to wire it this way, I have the live from the battery to my 2 pin starter button then from the button to the solenoid via a 50 amp fuse ( is this fuse to big ) and from the solenoid to the starter motor, and I have the negative wire from the battery directly to the solenoid then from the solenoid to ground, the reason I am thinking that the negative doesn't need to be as big as the live is because the negative poles on the solenoid are a lot smaller, can anyone please advise. Thanks Jay jay
Click to expand...
I am surprised you have wired heavy cable through your starter button and have an unusual starter solenoid that is switching both positive and negative. Most just switch the positive. Usually a solenoid will only have smaller terminals for the coil of the solenoid. One will be to neutral the other to your starter switch. You most definitely don't want a 50 amp fuse to protect the wiring of a coil on a starter solenoid!
In my experience most outboards have a heavy duty unswitched negative to the battery and a heavy duty (optionally fused) feed to starter solenoid.
 
The only thing I have wired at the moment is the short live from the solenoid to the starter motor heavy gauge ( at the moment ) my intention is to run the heavy live from the battery to the other side of the solenoid and also from that point a small live back to the starter button and from the other point on the button to one of the small connectors on the solenoid and from the other small connector on the solenoid to ground and finaly the heavy negative cable from the battery to ground at the starter motor, please advise if you think this is ok. Cheers Jay Jay
 
You must log in or register to reply here.

Share this page

Top