Merc OB dies cannot restart

[bigbobby]

I have a 1991 Mercury OB (Pontoon boat) that quits running after 20-30 min. of running time. brief back ground: Had fuel filter changed at start of season. Boat ran fine for a couple of runs then quit and could not restart. Noticed slow fuel drip from bottom carb. ? boat towed to marina. They did compresion & spark check- all OK. They replaced oil line hose & adjusted carb linkage. Boat ran fine for another 30 min than quit & could not restart. HELP What might be going on PS fuel only drips when not running

 

[MH Hawker]

Re: Merc OB dies cannot restart

carb float needle valve isn't seating

 

[Faztbullet]

Re: Merc OB dies cannot restart

When it quits check the spark as it sounds like a stator failing due to heat/age or rectifier....

 

[bigbobby]

Re: Merc OB dies cannot restart

carb float needle valve isn't seating

MH Hawker: Is that a big job? I guessing rebuild lower carb

 

[ondarvr]

Re: Merc OB dies cannot restart

Depending on where it drips from it may have no effect on it not starting, could be just a loose screw or leaky gasket. If it starts in the beginning and runs fine until it dies, it is most likely not the float needle causing the problem, more likely an electrical problem if it runs for about thirty minutes and then dies.

 

[Toddboat]

Re: Merc OB dies cannot restart

There is another possibility. The leaky carb could eventually build up enough fuel to flood the motor. This would explain it not starting again. It would start the next day, after the fuel has evaporated. Next time it doesn't start, put the throttle all the way open (still in neutral) and try starting it that way. Try several times. This gives it enough air to offset the excess fuel. Or try removing the spark plugs and turning the motor over a couple times. This will force exess fuel out. If I'm right and it's a flooding issue, you should clean the plugs because they foul when flooded.

 

[bigbobby]

Re: Merc OB dies cannot restart

There is another possibility. The leaky carb could eventually build up enough fuel to flood the motor. This would explain it not starting again. It would start the next day, after the fuel has evaporated. Next time it doesn't start, put the throttle all the way open (still in neutral) and try starting it that way. Try several times. This gives it enough air to offset the excess fuel. Or try removing the spark plugs and turning the motor over a couple times. This will force exess fuel out. If I'm right and it's a flooding issue, you should clean the plugs because they foul when flooded.

thanks for the help. One question I cannot start engine with throttle in wide open position. I have a single throttle lever.

 

[MH Hawker]

Re: Merc OB dies cannot restart

I would listen to what fazbullet and ondarvr says, they know their stuff.