Apparent Electrical Issue (1999 Johnson 150HP) - Sorry Long

It has been a trying start to the season for me. Bought this boat last year as my first bass boat and it has a 1999 Johnson 150 on it (J150PLEES 1999). Ran great all year last year. First time out this year is good until the afternoon and we turn key and click. Tapped on solenoid and got her started and back to the dock. I replaced the starter solenoid and everything seemed fine.

First time out after replacing the solenoid and boat starts up and runs a few times from spot to spot. All of a sudden turn the key and click again plus I lose all tilt/trim. Tap solenoid after removing the hood and got her started and tilt/trim came back.

So finally going through manual last night and checking a few issues in my driveway. Engine was turning over and tilt/trim okay (but seems slow on the up) but sounds like solenoid is rattling inside with the hood off. Eventually both systems stop working and repeat tapping on solenoid and both come back.

Long story short, I am out of ideas. Replace solenoid again or is something else elctrical wrong that keeps causing the solenoid to go bad? Thanks for any help or insight that I can get. Mechanic may not be able to look at it for awhile so I am trying to see if this issue can be solved by myself.

Anyone have any advice on this issue. Real question is what would cause a solenoid to go bad, would low voltage from a short cause that?

Check your battery connections if you have wing nuts on the cranking battery replace them with stainless steel hex nuts and lock washers or stainless nylon insert nuts. The positive connection from the battery to the solenoid also has the positive lead to the voltage regulator on it. This also has the main 20 amp fuse. When the trim stops it is because the circuit for the main power is interrupted. Check your ground connection on the starter. If needed use a dremel tool and clean the ground on the starter. If the lock washer is missing from the bolt that connects the ground to the starter replace that too.
Battery voltage should be ~ 12.6 volts without the motor running. You can connect a volt meter at the solenoid and have an assistant turn the motor over with the plug wires disconnected to prevent starting and monitor the voltage there. Then move to the post on the starter and check for voltage drop.

Thanks Championman. I will check this tonight when I get home. My cranking battery was using wingnuts and one was a little loose so I am wondering if that could have fried the solenoid. I am going to change these as well tonight.

Yessir, loose battery connections are the death knell for marine electronics.

Did as instructed as far as cleaing connections and ensuring everything was tight and here are the results. Voltage at battery good.

When we turned the key, the voltage on both sides of the solenoid (red in and black out) was the same as well as into the starter (the plate that connects black from solenoid to starter post).

This just doesn't make sense to me but I am probably not understanding correctly. If I am getting power thru the solenoid and it is not turning over then it is probably the starter but why is trim not working. I was thinking this was the same connected issue but maybe it isn't? Sorry for all the questions but I am trying to learn. I appreciate the help.

I believe the tilt motor is powered from the main battery connection at the starter, if you didn't remove the battery cable at the starter you need to do that and clean all the terminals there to bright and shiny.

Those battery wingnuts can blow ignition components if they get loose, thrown them away.