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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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Volvo marine engine 5.8L gets to 3000 rpm and starts

Customer Question

Volvo marine engine 5.8L gets to 3000 rpm and starts stalling. fuel pump is 60 days old and just installed new relay. why is engine stalling. once cool, it will run ok for about 15 minutes
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.

Hello. My name is Tan.

The engine is starving for fuel. Run the engine on a different fuel source. Does it run better?

Disconnect the fuel supply line going to the engine. Plug the fuel line. Now get some fuel hose and a gas can. Connect the fuel hose to the engine and stick the other end of hose in the gas can. Secure the gas can go run the boat. Does it run better or the same?

Customer: replied 2 years ago.
Tank was full of 93 octane fuel but I add 8 gal of 87 octane and then couple of house later started having problems. Gas tank is 35 gal
Customer: replied 2 years ago.
At steady hand on throttle rpm flucates up to 5000 rpm
Expert:  Tan replied 2 years ago.

This is a process of elimination. Your symptoms are of fuel starvation. So I start at the fuel source and work my way towards the engine. When we eliminate the boat side fuel system it will tells us if we have an engine issue or a fuel delivery problem.

This is the simplest and easiest test that can be done with minimal trouble shooting tools and skills.

The most likely issue here is debris in the fuel tank pick up tube clogging or restricting the anti siphon valve.