1978 evinrude surges between 3 & 4 thousand RPM

[Mike Sells]

I have a 1978 evinrude 150 that surges between 3 & 4 thousand RPM. Carbs have been overhauled. Runs good and steady over 4 thousand. But over 4 thousands really like the gas lol. I really like to run it between 3&4 less fuel burning. Other than surging motor run excellent. Can any one help thanks Mike

 

[boobie]

Re: 1978 evinrude surges between 3 & 4 thousand RPM

Will the problem go away if you pump the primer bulb ??

 

[emdsapmgr]

Re: 1978 evinrude surges between 3 & 4 thousand RPM

If it runs ok at WOT, the fuel pump is probably ok. Surging is sometimes related to the 3 carbs being out of sync. Pull the airbox cover off and make sure the carbs all open equally throughout the range of each carb's throttle plates. If one carb is open slightly more than the others, you can get surging. There are screw adjustments on the top and bottom carb to adjust/sync the throttle plates. These engines were never known to be fuel efficient-but they make a lot of torque.

 

[Mike Sells]

Re: 1978 evinrude surges between 3 & 4 thousand RPM

Will the problem go away if you pump the primer bulb ??

Ill try that and see tyvm Mike

 

[Mike Sells]

Re: 1978 evinrude surges between 3 & 4 thousand RPM

If it runs ok at WOT, the fuel pump is probably ok. Surging is sometimes related to the 3 carbs being out of sync. Pull the airbox cover off and make sure the carbs all open equally throughout the range of each carb's throttle plates. If one carb is open slightly more than the others, you can get surging. There are screw adjustments on the top and bottom carb to adjust/sync the throttle plates. These engines were never known to be fuel efficient-but they make a lot of torque.

I checked them before ran this spring but will check again. Thanks Mike