Mercury 150 outboard solenoid strating problems

Hi everyone this is my 1st post and I need some input on a problem I had this weekend. I have twin 2002's, 150hp Mercury outboard saltwater, carb motors on my boat. in the morning they started up and away we went about an hour run. after fishing awhile we wanted to move and the starboard motor wouldn't start. all it would do when the key was turned was 1 click each time I turned the key. I was thinking Solenoid, I took off the cover and spun the starter gear by hand and tried a few more times the starter kicked on and the motor spun but didn't start, them the same 1 click. We started back on the port motor. This is were it get interesting after 15 minutes at 6 or 7 mph the port motor stopped and the same issue I turned the key and one click. now both motors are down. after 5 minutes of turning the keys the starboard spun for a second and luckily it started and got us back to the dock. At the dock I tried starting them and both started, I shut them off and tried again and that was it neither would turn the starter just 1 click with each turn of the keys. So I started checking first I charged both (new) batteries and they had 12.77 volts. I reinstalled them and checked the volts at the cable ends and at the solenoid all had 12.77 to 12.75 volts. so I ran a jumper from the battery to the starter and the starter spun like a top. again I was thinking solenoid. so I took it off and did a bench test I put a volt meter on the 2 small studs and had continuity, them the 2 large studs and no continuity them put 12 volts to the 2 small an heard the same click sound and had no continuity... I think that's when the current should go to the starter.. right? so to the question am I diagnosing the problem correctly? and is it possible that both solenoid would go within 15 minutes of each other? Is there anything that could have shorted both of them at the same time. Sorry for the long explanation but I wanted to give as much info as possible Thanks for any ideas resolving this problem

Re: Mercury 150 outboard solenoid strating problems

if you put 12 volts on the small studs, that's the control voltage side from the key switch and they closed, that's the clicking you hear and you had no continuity across the big studs, that's the power side, then its bad and even if it dose close any thing other that a 0 ohm reading shows it bad.

Re: Mercury 150 outboard solenoid strating problems

The solenoid is a high current switch, obviously. The small terminals send a control voltage into it and energize an electrical switch....solenoid. This pulls a large, flat, copper disc down on top of 2 not as large terminals....the internal ends of the large studs sticking out both sides. If the contacts are clean and smooth, you can run 200 or so amps through them easily, with no voltage drop to speak of. Over time, making and braking this connection causes the copper to pitt. This reduces the surface area and when it gets bad enough the current drops to a very low value.

So, with what you have said, especially with your checking the voltage where you did and the jumper wire working as it did it looks to me like you need a couple new ones. They sell them on here.

Mark