Starter keeps running

[QC Willy]

Starter continuously runs with key off. I’ve replaced the starter solenoid, starter and disconnected the ignition switch but it still stays running unless I disconnect the battery. I have. 2004 Mercury 50hp 2 stroke. Any thoughts??

 

[Chris1956]

Clearly you have it wired wrong, or some sort of power wire is rubbed bare and touching the starter circuit.

Disconnect the red/yellow wire at the solenoid. If the starter still spins, the trouble is likely in the motor harness itself. If the starter stops spinning, the trouble is in the boat wiring harness.

If still spinning, disconnect the battery feed to the starter solenoid. If the starter stops spinning, their is some voltage being sent to the solenoid from somewhere on the motor.

Remember the starter has a simple circuit. The battery is connected to one side of the solenoid. The other side of the solenoid is connected to the starter. A lot of motors use the starter solenoid battery side as a connection for all the hot cables. Your trouble may be found there by disconnecting each of the those "hot" cables one by one, until the starter stops spinning. That one will be the culprit.

 

[QC Willy]

So I disconnected the red/yellow wire and it still spins. Put that back on and disconnected battery feed to solenoid and it stops. In the second picture, what is the square black box that the wires fees in to?

 

[Fed]

One short stud on the new solenoid?
I'd want to know why.
The other end of that stud is probably a square shape to fit into the plastic housing so it can't turn, if it's not located properly it could cause the problem.
Have you been fiddling with the solenoid studs?

 

[QC Willy]

The bottom stud has additional red wires going to two relays which makes it look shorter. This condition was happening before I replace the solenoid.

 

[Fed]

Fair enough, all I've got is a stuck on solenoid as crazy as it sounds.

 

[Chris1956]

That black box has grey, yellow and red wires going to it. It is likely the voltage regulator.

I would remove all the wires on the battery side of the starter solenoid. Now put just the battery cable onto the solenoid. If the starter spins, you have a stuck solenoid.

If not, add each wire back onto the starter solenoid battery side, until she starts to crank. When that happens, you have found your culprit.

 

[QC Willy]

I’ve done everything, even replaced the starter solenoid again, and still the starter spins without the key on. On the bottom solenoid stud first is the wire going to the starter, next are 3 red wires (1 coming from the harness and the other 2 going to the the grey box you think is the voltage regulator) the last one on the stud the battery cable. The top stud has 2 red wires each going to a separate relay. The 2 smaller studs: 1 is the ground (black wire) and the other is the red/ yellow wire coming from the harness.
it all worked fine until I replaced the fuel filter, went to start it up and now I have this problem. I just don’t get why all of a sudden this started happening.

 

[Chris1956]

So you have the starter cable and the battery cable on the same stud? That is what you just said. That will do it every time....

 

[QC Willy]

That’s how it was when I bought the boat and just copied the wire placements when replacing the solenoid. Should I put the starter cable on the other stud that has the 2 red wires going into 2 different relays?

 

[QC Willy]

Sweet jesus, that did it!!! Huge thank you chris 1956!!!!!

 

[Fed]

Your description doesn't seem to match the pictures at all but anyway I'm glad it's fixed.

 

[Chris1956]

Well, The cable going to the starter should be by itself on one stud of the starter solenoid. The other bunch of cables, including the battery cable should be on the other stud of the solenoid.

I hope you got it

 

[Chris1956]

One more thing. If the voltage regulator wires were disconnected from the battery, and the motor was running, the voltage regulator could have broken.

Measure the voltage at the battery with the motor off. Now start the motor on the flusher, and increase RPM to about 1500. Measure the voltage at the battery. It should be higher than the first reading. If not the VR is bad.