buzzing solenoid?

After I replaced the main harness on a merc 50 HSP when I went to turn over the engine the solenoid buzzes. No click, no engagement of the starter, it just buzzes. Hard to believe it's the solenoid since I replaced it two weeks ago. Maybe. Thoughts?

Doc

Re: buzzing solenoid?

Maybe it's being hit with AC because the rectifier is not working.

Re: buzzing solenoid?

Take both your battery cables loose at both ends, Doc. Carefully clean them and reattach.

Good luck, and let us know what happens.

Re: buzzing solenoid?

Not sure about hitting it AC or how that could have happened. The cables are clean and tight. The buzzing sound is more like chatter or the opening and closing of the solenoid very fast.

Re: buzzing solenoid?

Swaped the voltage regulator this morning and that was fine. The starter tested okay, the brought the solenoid down to the local small engine repair shop and they couldn't get it to open an close. Off to buy a new solenoid.

Re: buzzing solenoid?

Solenoid wasn't the problem. I am still stumped.

Mercury ELP 50 hsp two stoke, three cylinder.

About two months ago I noticed the gauges when traveling, in the boat, the would go dead, then magically come back up. Then a few weeks later I couldn't start the boat and noticed all the gauges are dead, key switch dead, trim switch on the shifter handle dead. When this happened I noticed that if I use the trim switch on the motor the gauges go back up and the motor will start with the key switch.

I am thinking feedback through a ground activated the gauges.

All the grounds are tight and the problem is getting worse. In a bulletin board I read the main harness has a tendency to short out. So I swamped out the main harness all 20 wires. Now the solenoid chatters like it is trying to open and close very fast and the intermittent gauge problem still exists. The two I think are related. A bad ground?

Yes, I put back the old main harness in and the solenoid chatter still exists. I swapped out the solenoid and it's good, still chatters.

The black/yellow ground on the solenoid is grounded to the voltage regulator. I moved the ground direct to the starter. Turned the key and it tried to start. However it started to smoke and the wiring became very hot.

Replaced a good solenoid
Tested the starter with jumper cables and it's good
Trim relays, good
Replaced a good voltage regulator
Rev limiter, good
Unplugged the stator and trigger, good
Replaced a good main cable harness
Replaced a good key switch
Oil sensor, good
All the grounds are tight.
Cables from the battery are good and tight.

I know my trim level gauge has a short in it. That shouldn't be affecting the solenoid. Maybe there is a bad wire from the key switch to the main harness in the motor? A short inside the throttle? Ideas? What causes a solenoid to chatter?

Re: buzzing solenoid?

I you have not already solved the problem following the good advice you already received, you might try sytematically testing the circuits with a multi-meter to see if there is sufficent voltage where there should be voltage, sufficient ground where there should be ground, and sufficent continuity where there should be continuity. If you do this, you can't help but find the problem. The trick is knowing what to check and in what sequence. The Mercury OEM shop manual for your particular motor would have a wiring diagram and appropriate troubleshooting guide. The below linked starter troubleshooting guide is for my 150hp motor but it might help you as it will give you an idea of the general process. If you do some of the circuit tests (using a multimeter) and are still stumped, report back on what you did test and you will likely get some more good advice on what the actual problem may be. Replacing parts on a hunch (especially ones that do not even affect the starting circuit) is a more costly way to troubleshoot. Just my thoughts...

http://forums.iboats.com/attachment.php?attachmentid=26803&d=1240510980

http://forums.iboats.com/attachment.php?attachmentid=26804&d=1240510999

http://forums.iboats.com/attachment.php?attachmentid=26805&d=1240511009

Re: buzzing solenoid?

We solved both problems yesterday.

The intermittent gauges and starting problem was a short in the main harness going from the cannon/DIN plug extension from the motor to the key switch. That cannon plug was shorting out. The Merc dealer did not have cable in stock so we hard wired it by cutting off the cannon plugs.

The buzzing solenoid was two ground wires that we switched. It works now, but I think there may be some additional resistance somewhere. The solenoid through the ground wasn't getting enough voltage to the solenoid.