1986 Mercruiser quits running after 2 hrs of running time.

[mgquinton]

Hi everyone.

I have a 1986 Vanguard boat with a mercruiser 140r engine serial # 6805207.

The Problem: Boat starts and runs well for about two hours at 4,000 rpm. Then it just randomly quits. Can't restart. Took to boat mechanic and they diagnosed that it was the fuel pump so we had that replaced last year. This year we are having the same problem. Boat runs fine for about two hours and then quits. Mechanic thought it might be the ignition coil so we replaced that. Just got back from the lake. Same problem. Any suggestions would be greatly appreciated.

Engine was serviced by boat mechanic last year.

Michael

 

[jimbo_jwc]

Re: 1986 Mercruiser quits running after 2 hrs of running time.

Mine acted similar after determining not battery / alternator after two occasions it was the brgs going bad from water intrusion in lower unit . Last time it bound up and wouldn't turn over at all .Thought starter was bad. Pulled whole lower unit found gear oil water in bellows but didn't leak into engine compartment , removed top brg cap and found taper rollers from brg scattered and lodged in between gears . Check condition of gear oil for water first .

 

[mgquinton]

Re: 1986 Mercruiser quits running after 2 hrs of running time.

Mine acted similar after determining not battery / alternator after two occasions it was the brgs going bad from water intrusion in lower unit . Last time it bound up and wouldn't turn over at all .Thought starter was bad. Pulled whole lower unit found gear oil water in bellows but didn't leak into engine compartment , removed top brg cap and found taper rollers from brg scattered and lodged in between gears . Check condition of gear oil for water first . View attachment 205263

Just had boat serviced last fall by marine tech and there wasn't any water in the gear oil. If I let it sit out over night it will run fine the next day for about 2 hours.

 

[hivoltg]

Re: 1986 Mercruiser quits running after 2 hrs of running time.

If its running that long without issues I would lean towards something restricting fuel. Like the check ball in the fuel tank elbow sticking closed.

A clear inline fuel filter would help verify your getting fuel when it happens.