65 hp merc suddenly powers down

[rockytop93]

Its a 75 merc 650. Starts and idles fine. Runs ok at wot for a few minutes and then as if you would quickly pull the throttle back, it will slow down to 2500 to 3000 rpm. Throttle still wide open. By pulling the throttle back it will run along at the slower speed perfectly. pushing the choke button will cause it to slow down and the prime bulb stays hard. So don/t think it is fuel. Tried to test ign components but my clymer manual says they have to be checked by a merc mech with special equipment. Did test the coil(only one on this model) two of the tests ok the third should have read 57-74 ohms from coil tower to ground. Showed nothing. Any ideas anyone

 

[springbok]

Re: 65 hp merc suddenly powers down

I had a similar problem with a 6hp mercury.<br />Idles fine and runs great at wot but has the same problem you have after driving for a while, as if you put the throttle back quickly.<br />I figured out the problem, the o'ring seal for the fuel filter was missing and the fuel filter was sucking in air. After driving for a while it would suck in enough air to cause the engine to starve for fuel. I installed a new seal and now it runs great.

 

[rockytop93]

Re: 65 hp merc suddenly powers down

thanks, i'll give it a look over