Recently purchased a '78 Sea Ray with mercruise i/o drive and while it seems mechanically operational in all respects, there are a few things that need some attention.

First off, the trim up, up,out, down switch: This one requires you to push the up/out button and the up button at the same time to trim up. Is that normal? We had an old merc i/o when I was a kid and I do not recall having to push both buttons to get it to react. Shouldn't the up-switch trim up with a limited amount of travel, the down-trim down, and the up out-trim at a higher rate of speed all the way up when pushed with the up button? Again, it's been about 30yrs since I've operated one, so I could be mistaken.


The trim gauge is not working: Any links to a wiring diagram for this assembly so I can make sure everything is right before I begin replacing components?


Shifter and throttle cables: It wants to begin throttling up a tiny bit before it locks into forward or reverse. So, of course, it shifts hard into gear which I know isn't good for it. I'm assuming (yeah, I know) that it just needs some adjustment to correct this. Am I correct? Should I be looking to adjust the throttle cable, or the shifter cable? Any insight here?

Thanks for any help.

Jay

Yes you have to push both buttons if the control handle if I remember correctly has buttons on either side of handle the inside button is for trim while running and the outer is the trailer button. If that is the only way to trim up the trim limit sender is bad. The trim gauge not working is more than likely is the trim sender. The shifting problem is the transom cable is getting stiff. Need new transom cable.Sounds like the out drive needs service New trim sender and trim limit sender the senders come as a kit and shift cable with outer cable and new core wire and all hardware.....OPTI

The buttons on this one are on the dash, but I think I get what you are saying. I found a wiring diagram online this morning, I'll check all that out today to make sure it's not a butchering issue, then start chasing the gremlins. Hoping to find some wires not connected or hooked up incorrectly.

I found one reason the trim gauge won't work, the blue and purple wires that go to the sender are cut, obviously cut just behind the connector by the pump. Can't find the other end to connect them to, will have to dig deeper.

I also found what appears to be the travel limit switch, and found every wire that would connect to it cut as well, with no idea where they would connect either.


More research to do there.

Found the shifter cable anchor point loose and flopping around a bit before the cable actually moved anything. So I'm hopeful that might help the hard shifting issue.

I was told this is a two owner boat, though I take things like that with an amount of skepticism. And in this case I find it really difficult to believe that two people could be so inept at troubleshooting simple wiring issues as this boat has experienced. I have pulled out a crazy amount of wiring, stripped it all down to the factory stuff and found it to be in surprisingly good condition. I think instead of even trying to figure out what was wrong with something they just pulled more wires to whatever component was giving them a problem. Of course, they had stereo, amps, and all kinds of [censored] I had to remove the wiring for as well, but most of the non-stereo related wiring I removed can be reattached to the factory harnesses. I do have a couple of mystery wires in the factory harnesses to figure out their purposes, but overall I am confident that I have drastically dropped the fire hazard a couple hundred percent.