20hp Johnson push-button 'start' won't crank the starter ...

20hp Johnson 1997 model, J20CREUM. This has a push-button on the front lower pan to crank the starter.

My bro gave me this motor when it had the problem and he has $$ so he just bought a new OB and that dealer told him it is the solenoid. Well I gambled $50 on a new solenoid (for the ‘free’ motor) and same thing. There’s power to the lead side of the solenoid and I get 12.8 VDC between the red lead on one side to the yellow/red wire on the other side. But pushing on the start button doesn’t crank the motor over.

It has a rope pull start too and she fires right up, so that’s good. I wonder if my brother goofed something up :shock: when trying to diagnose it himself, lol.

On the other side of the powerhead at the gear shift, there's a switch to prevent starting in neutral. I get continuity when the shift is in neutral and my DVM goes to ‘open’ whenever I switch to forward or reverse.

Any other ideas of how I can verify/test things to get this puppy working?

One side of the solenoid should measure ~12V when the start button is pressed (as you already verified), but the lug on the other side should be grounded through the neutral safety switch.
edit:
Verify the ground side of the solenoid has continuity to ground when in neutral.
Also, does the starter crank when you apply 12V directly to the starter?

Good luck.
-jasper

Any chance of temporarily swapping out the battery for another one?. Even though you get 12 volt measurements, that doesn't mean the battery can put out the amps necessary to do the job.

Battery is fine, it cranked my 18hp & 40hp no problems. I found some info to diagnose them wiring, so I'll try that. Thanks!

Do you get anything when you press the start button? The wires are frail and corrode easily under the insulation. Could be a short in the wire. A short in the starter will act up and produce random results.

hot wire the starter with a set of jumper cables. Ground to engine frame, and touch the hot against the stud on the starter and see if it spins. If it doesn't, its a bad starter.

If it does, work backwards from there.

Lugoismad has it correct;

treat DC wiring like plumbing - start at the END first. Apply batt. power directly to the starter first; if it DOESN'T spin, you know what you need. If not, backtrack from there, one connection at a time using your DVOM.

If your faucet has no water coming out, you wouldn't start at your meter outside the house - you'd work your way back from the faucet.

You'll figure it out, I'm sure! Best of luck! Hopefully just a poor connection.

lugoismad said:

hot wire the starter with a set of jumper cables. Ground to engine frame, and touch the hot against the stud on the starter and see if it spins. If it doesn't, its a bad starter.

If it does, work backwards from there.

Click to expand...

I'd recommend against doing this as it can easily damage/melt the threads on that stud. If you're going to resort to testing it this way I'd recommend you connect the jumper cable positive clamp to the nut or cable end that is on the starter stud. Then when you're ready, touch the + from the other end of the jumper cable to the + on the battery. It won't hurt to melt or burn the top of the battery post a little and it's going to be replaced in the near future anyways.

But you've got a meter so I would use that instead. Connect the meter ground lead to the negative on the battery. The solenoid should have 2 large studs and 2 small studs. Check with the + meter lead and one of the large studs should show approx 12-13 vdc. Once you have verified that you have good voltage at the solenoid, move the + lead to the other large stud on the other side of the solenoid. Press the start button and see if you get any voltage. If you get good voltage there, move the + meter lead to the stud where the cable connects to the starter and hit the start button again. If you get good voltage there, you've got a problem with the starter.

If you did not get any voltage on the other side of the solenoid when you hit the start button you'll need to test the solenoid. With the - lead still connected to the battery, put the + lead on one of the small lugs on the solenoid and press the start button. You should see 12v on one of the small lugs (test both if necessary) while the start button is depressed. If you don't see any voltage at either one, you have a problem with the starter button, associated wiring to it, or the wire from the button to the solenoid. If you have voltage when the starter is pressed, you need to verify the other small lug is grounded. If the ground is good, replace the solenoid.

IMHO, the thread just above this one should be made a sticky.

richg99

Thanks JMichael - with that info I'm sure I'll diagnose it quickly, thanks so much!

PLEASE be cautious connecting to the battery positive post - one spark can ignite batt. acid fumes, potentially causing an explosion.
I have personally seen this happen....not a good thing! [-X

And, if you find that the starter is the culprit. It may only need a set of brushes. Lots cheaper than buying a new OEM starter or a just about worthless Chinese replacement starter.

You are welcome DaleH, I hope it helps you get your problem resolved. And Muzikman is right about being careful with a battery as it can explode. I probably should have mentioned that also. As far as I know it's only a problem if the battery is gassing (releasing hydrogen gas). This happens when the battery gets warm/hot from being charged at higher amp rates or when it is subjected to a high rate of discharge for a short time.
In the early 70's was working at a garage, I was disconnecting the charger cables from a customers car that had just been given a 1 hour fast charge (probably 25+ amps charge rate). I had flipped the toggle switch to off but unknown to me, the switch had shorted out and the charger was still on. When I disconnected the cable it sparked and the battery went BOOM. The acid was vaporized from the explosion and I was almost completely covered in a mist of acid (including face and eyes). It's not something I'd want to repeat. I got lucky that there was no permanent damage other than the clothes I was wearing and the battery. I'll never understand how all those pieces of the battery case missed me but they did.

JMichael;

It happened to me once as well, years ago - hard lesson learned, but never forgotten!

I was lucky as well; no lasting injuries.

We both are very fortunate not to have lost our eyesight.

Been much more careful ever since!

All a solenoid is is a coil of wire that is an electromagnet. Juice goes in one side of the coil and comes out the other side. These are the small wires. The electromagnet moves a piece of steel into the large stud contacts which switch your starter.
If you take a pair of old pliers and short the two large contact nuts together the motor should crank. It will probably arc and put a mark on the nuts on the studs but don't worry about it. Gear heads have been doing this since forever.
The little wires/contacts/studs should have good continuity between them. Almost zero ohms, maybe .2 or something. If it reads infinity it's toast. If you apply voltage to the electromagnet you should hear it click. At this time you should have almost zero ohms between the large terminals. Remove the large wires before you check this.
If you jump a large cable (jumper) between battery + and the stud on the motor, it should crank. Touch it to the nut of the stud. I have on occasion taken the starter off the motor, clamped a cable between the starter flange and battery negative, clamp a cable to battery positive and touch it to the stud on the starter. Hold onto it good because it should spin. If it doesn't the starter is broke. Then you have to take it apart.
FYI: Sometimes you can find compatible brushes at the auto store. In a pinch oversize brushes can be sanded down to fit.
Cheers

Thanks guys ... with all of the details to test the switch 1st, then onto the solenoid or the starter, I should be all set ... less the time to get to it, lol! I'll report back what I found ...