Engine Restoration Problem...

[Back into boating]

I’ve got a 1990 Mercruiser 3.0, 115 hp, 4 cyl engine that won’t stay on. It turns over and then shuts off.

Just a few days ago, it was running, but running hot so we replaced the lower impeller, thermostat and water pump.

Now the tilt is stuck in the up position (no problem with that prior to today) and the engine shuts off immediately after turning on.

Any thoughts on where to go next?

Is it shutting off because the prop is up? Again, there was no indication that there was any problem with the tilt or trim until today. It just clicks, the pump does not turn on.

Thanks in advance!

 

[tank1949]

I’ve got a 1990 Mercruiser 3.0, 115 hp, 4 cyl engine that won’t stay on. It turns over and then shuts off.

Just a few days ago, it was running, but running hot so we replaced the lower impeller, thermostat and water pump.

Now the tilt is stuck in the up position (no problem with that prior to today) and the engine shuts off immediately after turning on.

Any thoughts on where to go next?

Is it shutting off because the prop is up? Again, there was no indication that there was any problem with the tilt or trim until today. It just clicks, the pump does not turn on.

Thanks in advance!

More so than not, it is a ground somewhere that needs cleaning. It is my understanding that MC trim pumps have more power going up than down. Obviously check pump oil and clean solenoid contacts, including quick disconnect and GROUND!!!! Did you disconnect battery cables before making repairs? If you can hear trim motor running but OD is not going down, push it down with broom or shovel wood end. It may work itself free. Keep in mind, that your trim limit switch should be prohibiting your motor from cranking if OD angle is beyond threshold limit. I have experienced the same up and down problem many times. Good luck!

 

[Back into boating]

Thank you Tank1949! I disconnected the battery before each repair. The pump now clicks when the button trim or tilt button is pushed. Pump does not run. (It ran perfectly before I started to mess with the over heating issue.)

I will clean solenoids and grounds and let you know.

Is it possible that the battery is too low even though it’s brand new and has only been used to start the engine while boat is on the trailer 5-6 times?

Also, would the engine in the up position cause the engine to shut off immediately after starting? It used to run until I turned it off because it was too hot. Now the engine turns over and shuts down.

Thanks again!

 

[Scott Danforth]

you are trying to run it on the muffs, correct?

also, never run the motor with the drive in the trailering position. you will tear out the u-joints

if you leave the drive in the up position against the stops, many times the cross-pilot check in the pump gets stuck. sometimes you need a heavy individual to jump up and down on the drive while pressing the down button to get it to move.

 

[nola mike]

Another possibility is that you're getting power to the coil while cranking, but not while ignition is in the "on" position. If the engine shuts off immediately after you release the key from the "start" position, I'd consider that. But agreed that this sounds more like a bad ground or other wire connection. BTW, the trim limit switch shouldn't have anything to do with engine cranking I don't believe...

 

[Back into boating]

Thank you Nola mike and Scott Dandruff! Here’s where we are:

1. Hitting the pump with a hammer while pushing the Tilt button made the od go up and down but it sounded like metal against metal. The next time, even hitting it with a hammer did not work. The solenoids and pump are getting 12volts from the battery. Does this mean that I need a new pump?

2. For the engine, I do use muffs, but no water was getting to the top of the engine causing it to overheat even after replacing all 3 parts (impeller, thermostat and water pump. I took off the bottom of the OD again and blew it out with compressed air. A bunch of gray stuff came out of the bottom after forcing air through. That either fixed the problem or created a whole new one. I will have to check once the od is down again.

3. As for the shutting off after turning over, I took the air filter off, cleaned it with a toothbrush and it seemed to stay on. I was only able to test it once before the od was stuck in the up position.