72 125 hp Johnson -- can only go forward

bds85466 · Aug 13, 2007

I've got a 72 125hp Johnson. I was running it the other day without any hitches and shut it down for about an hour. When I started the motor back up (in neutral), it immediately engaged in forward. I quickly turned it off, and tried again and found that when I turned it on in N, it would go forward, and when in R, it would still go forward. Throttling the motor still made for more RPM's and nothing else seemed to be a problem, it just wouldn't N or R. I then shut it down to look at the motor, and then after that, I could not get it started again.

darrklim2 · Aug 13, 2007

Re: 72 125 hp Johnson -- can only go forward

Do you have electric shift? I believe that the one's with electric shift would default to Forward if something went wrong with the electric shift so you could at least get home.

Dhadley · Aug 13, 2007

Re: 72 125 hp Johnson -- can only go forward

That is a hydro-electric shift. Very different than a straight electric shift. Joe Reeves has some excellent info on them. Search his postings and you'll find all the info you'll need. They're extremely simple once you understand them.

One thing is critical -- they need the right gear fluid. They shift on hydraulic oil pressure.

darrklim2 · Aug 13, 2007

Re: 72 125 hp Johnson -- can only go forward

Dhadley said:
That is a hydro-electric shift. Very different than a straight electric shift. Joe Reeves has some excellent info on them. Search his postings and you'll find all the info you'll need. They're extremely simple once you understand them.

One thing is critical -- they need the right gear fluid. They shift on hydraulic oil pressure.

Thanks for the correction I wasn't sure what it was called exactly.

bds85466 · Aug 13, 2007

Re: 72 125 hp Johnson -- can only go forward

Yes this model is a hydro electric shift. Do you think it is more likely that it's a fluid problem or possibly a blocking diode? Can I rule out linkage issues?

F_R · Aug 13, 2007

Re: 72 125 hp Johnson -- can only go forward

Most likely electrical. At least that is where you should start the troubleshooting. Next would be check/change the oil if the electric checks out.

bds85466 · Aug 13, 2007

Re: 72 125 hp Johnson -- can only go forward

I'm also afraid of why it would not start afterwards. I haven't gotten it to start since. Is there a kill switch or something that gets triggered in this scenario that will not let the motor start again? Or could it possibly be the fact that it's having to start in gear, requiring more power??

F_R · Aug 13, 2007

Re: 72 125 hp Johnson -- can only go forward

No, it always starts "in gear" but instantly shifts to whatever gear the shift lever is in as soon as it is running. I can't answer the question. It will require a systematic checkout of the electrical system with a voltmeter. Anything else is pure guessing and a great way to waste money on unneeded parts. However, do check the 20 amp fuse. It should be in a rubber fuseholder near the starter solenoid on the powerhead.

EDIT: After re-reading your original posting, The fuse might very well be blown. When it blew, that's why it jumped into forward and also why it won't restart.

bds85466 · Aug 14, 2007

Re: 72 125 hp Johnson -- can only go forward

I've read the stuff by Joe Reeves, and I'll most definitely check that 20 amp fuse when I get off work. The fuse is located by the starter motor in rubber casing? Do I have to remove any major components to find it? What will signify that it's blown or not? Dumb questions, but I'd like to make sure I know for sure.

Also, with the posts from Joe Reeves, he lays out very good info, but it's not very consise from a procedure standpoint. When you're checking with the volt meter, does the motor need to be cranking? Obviously if my motor is stuck in F, I have no voltage going through either the blue or the green wire, right? How does his procedure help me in what to fix or replace?

just plain ole Bill · Aug 14, 2007

Re: 72 125 hp Johnson -- can only go forward

I have a '72 65hp Evinrude Triumph with Selectric shift. The voltages on the blue and green wires at the motor can be checked with the key in the 'on' position without the motor running. The Neutral button has to be pressed before the motor will crank over. With muffs on the motor my prop doesn't turn over when the motor is started. Your prop might turn because you have something wrong you'll need to trouble shoot following Joe Reeves procedures.

When I first got my motor the prop turned when started in neutral and would not stop turning until I found and fixed my problem. I was lucky..my problem was low lube in the lower unit. It freed up and started working correctly after I filled the lower unit, ran it for a while then changed the lube again and ran it some more. Good luck and be safe!

bds85466 · Aug 15, 2007

Re: 72 125 hp Johnson -- can only go forward

yeah, that's another thing about this, I don't really want to start/crank it unless I have to -- since it will send the prop into slice mode.

F_R · Aug 15, 2007

Re: 72 125 hp Johnson -- can only go forward

If everything is working properly, the prop will turn less than one revolution before it will shift into neutral. If everything is not working properly, all bets are off.

Check your voltages at the blue and green wires with key turned on and motor not running.

As I tried to say earlier, the fuse supplies both the starting and shift circuits. It is a glass fuse with a very thin wire inside that you can see through the glass. Wire burned in two = blown fuse.

bds85466 · Aug 15, 2007

Re: 72 125 hp Johnson -- can only go forward

Right F_R...that's obviously the first thing I will check whenever I get a moment! Thanks for your help thus far. I've got to get my hands on a multimeter.

bds85466 · Aug 15, 2007

Re: 72 125 hp Johnson -- can only go forward

I'm having a tough time locating that fuse and the correct wires to test. My terminal block looks like a mess. I don't clearly see any blue/green wires. Any suggestions? I do have a diagram key for my motor....

bds85466 · Aug 16, 2007

Re: 72 125 hp Johnson -- can only go forward

Can anyone help me hone in on these wires and the 20amp fuse that I want to check? For the fuse, do I have to take some casings apart?

F_R · Aug 16, 2007

Re: 72 125 hp Johnson -- can only go forward

They seems like they move that fuse holder all over at the whim of the engineer on duty that day. See the big red cable from the battery coming into the motor and attached to the starter solenoid? Attached to that same big terminal on the solenoid will be a pair of smaller red wires. Follow that wire and it should come to the fuseholder. Actually, I think it disapperas into the wiring cable that has the big plug on the end of it, but at some point it comes back out and you will see the fuseholder. It will be a thick, black, rubber thing in the wire. Twist the ends and pull to open. The fuse is inside.

F_R · Aug 16, 2007

Re: 72 125 hp Johnson -- can only go forward

This is what a fuseholder looks like. This is on a different motor though.

bds85466 · Aug 16, 2007

Re: 72 125 hp Johnson -- can only go forward

F_R said:
They seems like they move that fuse holder all over at the whim of the engineer on duty that day. See the big red cable from the battery coming into the motor and attached to the starter solenoid? Attached to that same big terminal on the solenoid will be a pair of smaller red wires. Follow that wire and it should come to the fuseholder. Actually, I think it disapperas into the wiring cable that has the big plug on the end of it, but at some point it comes back out and you will see the fuseholder. It will be a thick, black, rubber thing in the wire. Twist the ends and pull to open. The fuse is inside.

"That Wire"...is that the big red wire or one of the small red wires? I saw a big black thing that was probably 1.25" in diameter that had multiple wires going in and out. It also was connected to the frame (box, not actual motor) with a wire piece that held it and screwed on. To get at it you had to pull the wire piece off so you could pull it apart. It was tougher than heck to pull apart, so I assumed I shouldn't. Maybe I'll try taking some pictures.

F_R · Aug 16, 2007

Re: 72 125 hp Johnson -- can only go forward

No, that plug is WAY bigger than a fuseholder. You are looking for something about 1/2" in diameter with a couple of red wires going in and out.

EDIT: Look at the starter motor. Follow the big red cable from the starter--it goes to the starter solenoid. Look directly opposite that big red wire on the solenoid and you will see another big red wire--the battery cable. Continue looking upward from there and you should find the fuseholder.

Don S. · Aug 17, 2007

Re: 72 125 hp Johnson -- can only go forward

If the 125 is laid out like my '71 100HP Rude. Then on the Starbord side of the motor the Blue and green wires from the L/U pop out just below the Power head kind of towards the back.

From personal experiance should one or both of the wire open, the L/U will default and remain in Forward gear. When I was doing som L/U work I forgot to connect up those wire and the prop. was in Forward and slinging water from the muffs. Which I was happy to see should anything fail with the push buttons I can just unhook the wire and limp the boat home.

72 125 hp Johnson -- can only go forward

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