1986 115hp Merc. Surging can't run at full throttle.

[ccrider79]

I have a 1986 115hp Merc. Runs great in the driveway with a little sputter. I took it to the lake, to put it under a load and at full throttle it will only run at 1/2 speed with a surge every 30 to 45 sec. I've changed all fuel lines thought it was air. Please Help.

 

[tbjtib]

Re: 1986 115hp Merc. Surging can't run at full throttle.

Sounds like a switchbox,but tou have to find some one with a merc switchbox tester or try replacing one. Hard to tell which one is bad if you have two on you motor(inline six)