What could be wrong with my outboard?

Question

My husband and I went fishing with our boat last weekend and our motor, a 1992 2 stroke 48 hp Evinrude started acting strange on the ride back to shore.

On the way back, the motor seemed to have lost all power. At full throttle it would not accelerate to normal speed and the boat would not get on plane.

The boat trudged back to shore where we checked the battery (fully charged) and checked the gasoline (3/4 tank). I don't know too much about outboards, but I know that the carbs were rebuilt less than two months ago and the motor was working perfectly fine prior to last weekend.

Has anyone ever had this problem before? Does anyone know what could be wrong? I'd really like to go fishing again this weekend, so any help will be very greatly appreciated!

Thanks in advance.

Answer 1

My 1968 Johnson 33HP 2-cylinder 2-stroke outboard does the exact same thing. After a seemingly random amount of time of running the engine, the bottom spark plug gets fouled badly enough to stop firing, which results in loss of power exactly like what you describe.

Based on my experience with my motor, I would go directly to the spark plugs. Check them all to see how fouled they look. Test all of them to make sure they all spark. Replace any plugs that don't fire. If you do replace any, test the spark again on the new plug(s). If they now spark, then you're all fixed and ready to go. If they still don't spark, then it's likely either a dying distributor coil or the wires going to those particular cylinder(s).

Assuming it was a fouled plug: If it happens again in a short amount of running time (say, no more than 5-10 hours of running), then you'll probably want to seek further help or take it into a professional to be looked at, as there's something else wrong with the motor that's causing the plugs to become fouled...

In my case, my high-speed jets are set too rich (which allegedly is a direct cause of fouled plugs), and my bottom cylinder has a loss of compression (which I'm guessing can be a cause of fouled plugs). Either of these, or a combination of both of these, results in my bottom spark plug fouling to the point of failure after about 2 hours (ballpark, it's pretty random) of running time.

It could be other things as well, including restriction of fuel flow (like a dying fuel pump or clogged fuel filter), but that's the cause of the problem on my boat... Hope it helps..

Answer 2

There could be any number of problems.  If you know how, pull and check the spark plugs.  If they are clean, look for an ignition problem...loose wires.

Answer 3

Fuel line?

Answer 4

lots of things just recheck stuff you have checked already if not any of those things maybe just like other people have said old gas bad gas loose wires bad wires worn wires try opening the moters if u can

wish u lots of luck trying to find the problem

Answer 5

sounds like a hi-speed misfire.

compression test - should be about the same on both cylinders

spark test - should jump a 7/16" gap outside the cylinder on an inline tester

troubleshoot fuel line as described above

all else ok, check the carb float heights & float valves for sticking

see if you got an obstruction in a hi-speed jet

Answer 6

Its either a fuel supply problem or one of the coils to each spark plug may have gone out. Have each coil checked out. They are known to go bad due to age. One way to tell is take a spark plug out one at a time and insert back into the spark plug wire. Touch the end of the plug to the engine block while holding the plug wire cover. Have another person to bump the starter. This needs to be done in the dark. You will see the plug spark if it and the coil are functioning properly. If they all are then you have a fuel problem. If a coil has gone bad they are simple to replace.

Of course be carefull. Keep hands away from the flywheel and make sure there are no open gas or fumes when you do this test.

Also was the primer bulb in the fuel line firm or flat? Was the vent on the gas tank open?

Answer 7

Bad gas,old gas,not enough oil,a rope tangled in the prop, fuel line clog, water in gas, or gas line, sugar or salt in gas tank,or gears may be bad.  I hope this helps.

Answer 8

Check the impellor, it may be worn out so it won't be cooling the engine and not allowing the outboard to run at 100%

Hope this helps