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Engine losing power

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Dbt1965

New member
What would cause 5.7 l engine at full throttle to come to stop. Replaced fuel pump since low pressure, replaced distributor, filters, checked electrical connections. Runs good for 30-69 minutes full throttle, then slowly slows down on own
 
My best guess: Fuel starvation due to a plugged anti-syphon valve, or an overheating electrical item (like the switch box or coil).

Jeff

PS: Running it at full throttle for "30-69 minutes" is looking for trouble--this is not an electric motor! You have to 'breath' the motor, pulling it back a bit. Have a heart!
 
Total Marine engine life ( per the engineers at the companies that make them) at Wide Open Throttle, is measured in tens of hours, low hundreds at best... For decent engine life they recommend running continuously (cruise) , i.e. more than a few seconds at 80% of maximum observed wide open throttle RPM...PROVIDED that the observed maximum RPM is within the specified maximum rpm range for that particular engine.... on many Merc's that number is on a decal on the flame arrester. 75% rpm gets even better life.
 
fastjeff said:
My best guess: Fuel starvation due to a plugged anti-syphon valve, or an overheating electrical item (like the switch box or coil).

Jeff

PS: Running it at full throttle for "30-69 minutes" is looking for trouble--this is not an electric motor! You have to 'breath' the motor, pulling it back a bit. Have a heart!
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Running across lake at full throttle, not at pier, stop, wait few minutes it goes for awhile but stops again or just spits and sputters
 
Start at the bottom of fuel tank the pickup tube,then moving forward to fuel lines,filters, water/fuel separator,all the way to carb. Need to get your hands dirty!!
 
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