Loss of power on evinrude outboard boat motor. Can anyone help?

Question

I had a major loss in power. You can throttle almost half way then it just kind of boggs at the same speed no matter how much gas you give it. I think that the choke is stuck because it is running rich at the plugs and it happened after the choke was hit to many times. The motor is a 65HP 1971 Evinrude. Can anyone give me some advice on what to try to get it back? Thanks!

Answer 1

Give this a try,,,,,, remove the air horn & look into the carbs while someone else is driving the boat. You'll see fuel coming up outta the main jet. If there's crap in the float bowl that's blocked the main jet, ya won't see the stream of fuel.

Answer 2

the choke on this engine has a manual overide. make sure that it is in the off position when the engine is warm. if the spring linkage from the elec. choke solenoid is broken/disconected the engine can suck the choke closed when it builds up enough vacum (approx half throttle). this will cause the engine to flood at higher rpms but not affect idle. this engine has a battery cd ignition system. it is very very sensitive to battery voltage. it has a pulse amplifier (like a modern cd module) , points under the fly wheel, and external coils. it also has a ring type distributor cap. this system worked very well, but not many mechanics understood it. check to see if your problem is spark or fuel related. then if ign related check the spark output at the plugs. then run the engine with a timeing light on each plug wire and look at the light. run the motor until it starts to run bad. do this for each plugwire. this will alow you to examine the spark while running and you can tell which cyl is affected and when. repeat question with results good luck(ps there is a special troubleshooting guide for this motor from omc, let me know if you want one as they are obsolete now) almost forgot what plugs are you using? this system is very particular they should use the perma gap or donut type only!!

Answer 3

Has the Eng been sitting for a while if so than chances are the cards need cleaning.Easy fix pull the front cover off the carburetors..With a 7/16 wrench in the front bottom of each carb there is a 7/16 brass bolt remove an get some carb cleaner with red tube on end insert inside an you will feel the main jet?Spray away it will come our the center of the carb when clean.Hope that helps.also see if you have the manual choke 1/2 on??

Answer 4

If the choke is stuck then you would notice it at low rpm too. It would run rough at an idle. It could be that you have fouled plugs, or a bad coil. As old as it is, nothing is going to be electronically controlled, so start by looking at whether or not it is getting spark. If it is, then you more than likely have a fuel problem. In that case you should start with the carb and work your way towards the gas tank. It could be that your fuel bulb is not working the way it should. the quickest way to see if you are getting spark is to pull off one spark plug at a time while it is running and see if there is any difference in the way it runs. If you remove a plug wire and the engine does not run any differently, the you know what cylinder to look at. I would change the plugs first and see if that makes any difference, since an outboard that has run rich will foul plugs extremely fast. If there is no problem with the spark or fuel, then you are probably going to have to look at the internals to make sure no valves are stuck and no gaskets are broken, but it sounds to me like this is a simple weekend fix.

Answer 5

If you hit the choke to many times it's probably broke. The obvious thing to do is replace. Take the choke off and run the engine by hand to see if the this is your problem. I would bet your shooting in the right direction. Good luck

Answer 6

i HAVE 150 EVINRUDE ,MOTOR RUN GREAT UNTIL ,I SWITCHED TANKS NAND IT WOULD NOT PLAIN OUT AND LOST POWER