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Dominick
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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Have 1982 70 HP evinrude outboard, starts up and runs fine

Customer Question

Have 1982 70 HP evinrude outboard, starts up and runs fine for about 15 minutes, about 30 knots wide open then begins to bog out and only runs about 15 knots. Let it cool down runs fine for about another 25 minutes and same problem occurs.
Submitted: 2 years ago.
Category: Boat
Expert:  Tan replied 2 years ago.

Hello. My name is Tan.

You have one of 2 things going on here. 1) fuel starvation 2) loss of spark. The first one is easy run the boat till it acts up squeeze the primer bulb does it run better? The other one requires the use of a timing light to check spark when engine is acting up. Connect the timing light to the top cylinder run the boat till it acts up. Watch the flash of the timing light. The flash should be steady with no dead spots. If that cylinder is firing good move to the next cylinder. Do this test on all 3 cylinders. If you find a misfire swap that coil with a good firing cylinder. If the misfire moves then the coil is bad replace the coil. If the misfire stays you have another ignition component failing. Either the power pack or the timer base.

Do these tests and post back with findings.

Customer: replied 2 years ago.
I switched the fuel line and avoided my fuel seperater and plugged fuel line directly in from the gas tank. The fuel bulb is hard to start off with but gets a little softer but engine runs fine. Tried pumping fuel bulb when engine start to bog but does not make any difference
Expert:  Tan replied 2 years ago.

Ok we need to do the spark test with the timing light. If you have a misfire the engine will bog.

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