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Late 80's model mariner issues

Yote

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Alright, so this was my grandpa's boat. It sat for a few years before he died and I got it. I had the carbs rebuilt last year, new batteries, and took it out. It ran really good the first part of the day, then almost sank. Apparently the hose that drains the livewell was disconnected in the hull, so the boat was slowly filling up with water all day. By the time I noticed it'd come up to where that hose was supposed to drain out and was really coming in fast. Water was lapping over the back of the boat. (it's a late 80's glasstream). So we try to high tail it out of there, but even with the gas pegged it wouldn't break plane and was really slow. But we managed to get it out of there.

I rerouted and fixed the hoses so it wouldn't leak and installed a new bilge pump. Took it out yesturday and it fired right up. But still ran like it was under a serious load before dying and wouldn't crank again. I'd also replaced the plugs and cleaned the fuel filter before leaving. It'd ran fine when parked in the drive way on the hose.

I don't even know where to start looking for problems now. Any ideas? What if you need more info, what do you need?

It's a 40hp oil injected, but my grandpa removed the oil injector part so I premix my gas, 50:1. Two cylinder, 88 or 89 year model.
 
First thing in order is a compression test before you do anything else.

I would be happy with over 90 psi in both cylinders, over 100 would be perfect.

Until we figure out whether the pistons have welded themselves into the cylinder(s) or otherwise failed, everything would be a guess.

I didn't see "serviced the waterpump" in your list of things done after the motor had been sitting around.
 
First thing in order is a compression test before you do anything else.

I would be happy with over 90 psi in both cylinders, over 100 would be perfect.

Until we figure out whether the pistons have welded themselves into the cylinder(s) or otherwise failed, everything would be a guess.

I didn't see "serviced the waterpump" in your list of things done after the motor had been sitting around.

Some water pump part was replaced in the lower, and (after the dirt dauber nest were cleaned out) there was a steady stream of water out of the motor while it was running. Will see about that compression test tomorrow. Thanks for your reply.
 
Showing 125 psi for top cylinder and 120 for bottom. 3 tries each. No readings under 120 and pressure did not fall off.
 
Bit more info. Don't think it's related, but I replaced the fuel line piece that connects to outboard, as the seal had gotten punctured. Squeezed the ball and the fuel filter filled. Then when we took it out, the primer ball would never get "tight" and sounded like it was blowing back into the fuel tank, so I replaced that today, but its still doing it. I emptied the fuel filter and it wouldn't fill when squeezing the primer ball either. And yes, the arrow is facing the right way. About 1/2 tank of (new) gas.
 
I don't think so. It drained fuel and you can hear it blowing fuel/air back into the tank with every squeeze. I pulled it earlier and it drained fuel. I guess I'm going to replace that whole line (or maybe all the lines) and the piece that connects it to the fuel tank next.

The motor ran for a bit, but the fuel filter never emptied. I'd think if it was anything from the line back to tank the fuel filter would've emptied before the motor died.
 
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