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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 1978 80hp mercury. it starts and runs good but at

Customer Question

I have a 1978 80hp mercury. it starts and runs good but at about 3500rpm it quits as if it ran out of gas
Submitted: 5 months ago.
Category: Boat
Expert:  Tan replied 5 months ago.
Hello Mel. My name is Tan. Will the engine restart when it quits?Have you tried squeezing the primer bulb when it get up to higher rpms?Have you tried another fuel tank to eliminate the boat side fuel system as a cause for the issue. If you haven't tried any of these try then and post back with findings.
Customer: replied 5 months ago.
I did squeeze the primer bulb-did not work
the motor will restart
I disconnected fuel line from carb-squeezed bulb-plenty of gas
could it be carb trouble
Expert:  Tan replied 5 months ago.
How about the choke when you get to higher rpms activate the choke. Does it run better? If the engine picks up rpms then you have a carb issue. All of these tests have to be done when engine is acting up under load.We need to do a compression test also.Now it is possible you could have an ignition issue. The test will require 2 people and a timing light. One will have to connect the timing light to one cylinder at a time to check the spark on each cylinder. Watch the flash of the timing light on each cylinder. The flash should be steady.

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