engine pulse problem at crusing speed

[dawavegod93]

I have a 1998 40 hp evinrude on a 13 whaler and recently the motor has been (at crusing speed only) studdering and then opens up, studdering and then opens up. The timing and plugs are all good. The motor is firing on all cyclinders just seems that it isnt getting enough fuel so it comes down in RPM and than gets fuel and comes back up. When the motor studders and i give it gas it takes a second and than opens up. Could it be the fuel pump is going???? And suggestions would be great... Thanks

 

[R.Johnson]

Re: engine pulse problem at crusing speed

If it will run at full throttle, I doubt the fuel pump. More than likely dirty carb's. I have seen this problem on the twin forty, Take the carb's apart, and not really see anything wrong. Put in a new kit and it clears right up. Use the OEM carb kit in this engine, not after-market. A pressure, vacuam guage is a cheap investment when checking the fuel system along with a OEM service manual to give you the correct spec's.