Mercruiser 165 (GM 250) starter issue questions

[ErikF]

Hello Everyone,

I have an issue with my starter/starter solenoid (and possibly more) that's giving me fits.

I've run through all my wiring and nothing seems amiss, everything matches up nicely to the diagram in the service manual.

When I start the engine with the key switch is will start but the starter will not disengage when the key switch is moved from "start" to "run." When the key switch is turned to "off" the engine dies.

I have not pulled the starter yet so it is possible to starter pinion is stuck on the flywheel and is just never moving engaging or disengaging.

I also noticed that when the engine is running if I remove the yellow wire from the solenoid on the starter the engine will die immediately like power is being cut to the coil.

I'm going to pull the starter as soon as I finish this post and will post anything I find. I think the solenoid is bad but I'm not understanding how exactly it failed, any insight is appreciated!

-Erik

 

[ErikF]

Re: Mercruiser 165 (GM 250) starter issue questions

Okay I've pulled the solenoid off and here's what I'm seeing. Apologies in advance for not having any pictures, I'm currently without a camera.

The backside of the two large posts where the contact the disc show spots of arcing. The disc has arc marks all the way around. Post "R" has a spring steel arm attached but it looks a little too low to be in contact with the disc 100% of the time. Post "S" is attached to a wire that goes down into the solenoid.

The solenoid is somewhat corroded but nothing really sticks out as broken. The arm going down to the starter seems to move okay so I'm pretty sure the pinion on the starter is fine. All springs are accounted for and none are broken.

-Erik

 

[ErikF]

Re: Mercruiser 165 (GM 250) starter issue questions

I think I'm getting somewhere. The wire from the solenoid to the coil provides full voltage to the coil when the starter is engaged but is supposed to disengage when the starter is stopped. Logically this is telling me that the engine starts & runs when the starter is engaged because the coil is getting power from the solenoid. When the starter solenoid disengages the power to the coil is cut and the engine stops (because I most likely have an issue with the resistance wire going to the + post on the coil.

Does this make sense? Still doesn't explain why the solenoid stays latched until the key is in the "off" position.

I'll go measure voltage to the coil with the key in "run" position to see if my resistance wire is intact.

-Erik

 

[alldodge]

Re: Mercruiser 165 (GM 250) starter issue questions

My first thought is your key switch is hanging or crossing contacts. The YEL/RED wire supplies power to the slave solenoid to start the engine, once released it removes power to the slave solenoid and the starter stops. Looks like you may need a new key switch.
Try this;
Remove wires from switch, momentarly touch RED/PUR wire to RED/YEL and see if it cranks, remove contact and it should stop and die.
Next
Connect RED/PUR to PUR, then momentarly touch RED/PUR to RED/YEL, once engine starts release contact RED/PUR to RED/YEL.

If the engine keeps running without starter being engaged replace starter switch. If something else happens let us know.